Welcome...There is a wealth of knowledge here. Don't know your budget but for sports I shoot with a Canon 7DII. Lenses make a difference, for outdoor I use the Canon 70-200 f4L, indoor use a Tamron 70-200 f2.8 with great results from both. IMO don't think a prime will get you the results you're looking for in sports. FPS to me are important in sports photography. You may only have 1 or 2 good shots but they are the keepers.
Over the years try to think more of what I will need for the day trip. Always carry 2 extra batteries, an extra SD and CF card, a monopod (if needed) and lens wipes. If doing street stuff mount my 24-70 f2.8, Sports the 70-200 f4 or 70-200 f2.8, family events a 50mm lens. Except for the monopod and camera everything fits in my pocket. I've done the backpack thing and found most of the gear I didn't need or use and hauled it around all day, some may feel the need for more but I feel careful planning helps lighten the load.
I'm fortunate to have both. Each have their place in what I shoot. I'm a Canon user and for sports my 7DII is the best. For indoor, portraits and family events I like my 5D. The results from both are great IMO. Budget plays a big part in cameras and lenses. All but two of my lenses are full frame. My favorite for outdoor sports is my Canon 70-200 f4L, for indoor sports use a Tamrom 70-200 f2.8. Indoor full frame like the 50mm. Does it really make a difference FF or crop? If I had to choose one over the other the 7DII wins...Again your budget plays a big part...most of my $$$'s are in lenses.
I use a Samsung Galaxy Tab A to fly my Phantom Drone and use lightroom mobile and it works.. Might not be the fastest but does work just fine...Bought it a few months ago refurbished (In the USA) from Amazon for about $125.00.
That's a great inexpensive fix for sure. If in the future you need repair use the Canon repair center. They repaired my old 5D Mark 1 last year (which needed no parts, thank god as they no longer make them) and was in need of a good cleaning for what I consider a very reasonable price seeing it had over 99,000 clicks on it. Used the east coast facility and they were in touch me each step. They took care of the nag I was getting, cleaned the camera and sensor and gave me (to my surprise) the actual click count. It was worth the $125.00 I paid. This is my backup camera but still use it often. Their customer service is the best. I have used them for repairs on DSLR's, video cameras and lenses and have NEVER had issue.
The Tamron 70-200 F/2.8 lens is a great lens. Use it for indoor sports and get great results. Don't have the G2 series but have the series just before that. The Sigma Art lenses are all fantastic lenses, I own one and walk with it most of the time...Great investment...
The Tamrom 70-200 F/2.8 Di VC USD lens for indoor sports does a great job, outdoor sports use a Canon 70-200 f4L (no IS) and find that exceptional. For my walk around lens like the Sigma 24-70 F2.8 IF EV DG. Yep I still use my nifty 50 a bunch for family events mostly indoors. As far as extenders I have a 1.4X extender for my Tamron and find it does quite a good job (when needed). Had a 2X and sent it back as the results were not to my liking. I can say that a Tamron extender on a Tamron lens works better than that extender on the Canon lens. 85% of my shooting is done with the 24-70 and the 70-200 f4...Those are my favorites.
My favorites for New gear is Cameta after visiting them a couple years ago and establishing a go-to very knowledgable person. For used gear I use KEH. Never had issue with either company.
I find KEH for buying and selling to be the best. Have had experience with both. B&H and Adorama are OK BUT buying and selling good used equipment is KEH's business and they do great at it. Did not realize Amazon bought used gear.
Few things to consider, if in the future you are planning to upgrade to a full frame camera than go with the 24-70. I have a Sigma 24-70mm F2.8 IF EX DG lens and it's my favorite walk around lens. I've had it a few years and like the results. Use it on my 5D, 5DIII and 7DII. The results on all 3 are very good. Investing in good glass is never a mistake. Using it on my crop 7DII the results may not be the same BUT still are very acceptable. Own a Tamron 70-200 F2.8 (full frame lens) and use it all the time on my 7DII for sports photography and absolutely love that lens and the results. Canon, Tamron and Sigma make great lenses. I would put my money into lenses.
I'm not a big fan of filters I've tried a bunch of quality filters and prefer shooting without them but lens hoods are a must to me for protection.
In my experience with converters if it's a Tamron lens use a Tamron converter. If it's Canon or Nikon use their converters, converters appear to work better with their own brand lenses.
Being a Canon user the 5D markIV would be my camera of choice. Depends on what you're shooting, I love my 7DII for sports and some wildlife which is what I shoot most. For portraits and indoor (low light) love my 5D, when I travel and want to go light my T5i and 2 APS-C lenses do the job. Now here's the question, what lenses do you have or plan on buying? Good glass is not cheap and that's where I would put the money. Most of my lenses are full frame lenses and can be used on any of my cameras. There are 3 lenses IMO that cover just about all the bases, all are full frame lenses 24-70/ f2.8 L, 70-200/ f2.8 L, and a nifty 50mm f/1.8. Set a budget get a great camera body be it Canon or Nikon but leave a bit left for some great lenses. Tamron and Sigma make some great quality lenses for both brands.
In my experience with extenders find that a Canon extender works the best on Canon lenses and a Tamron converter works the best on Tamron lenses. I have a Tamron 70-200 f/2.8 ISM VB lens and a 1.4X extender and the results are very good. Have a 70-200 F/4 L Canon lens and find the extender works with the Canon lens but the results are better using the Tamron lens. Purchased a 2X extender at the same time and returned it. Did not care for the results of the 2X. The Canon 1.4X works much better on the Canon lens. Use the 1.4X on both my 7DII and 5D with very acceptable results. I shoot a lot of sports and find the 1.4X on my 7DII to grab nice pixs...Your pictures will degrade a bit...