Look at the Sony a6000 line. The 6000, 6300 or the 6500 depending on your budget. Lens- 16mm 2.8 sells for around 250.00 a 22mm 2.8 for about 300 and a 35 1.8 for about 450. Small light weight cameras, great for street and travel photos.

Sony a6500

try using a tripod for longer exposures

Water falls and moving water.

Yep you can do this. You have the right equipment and know how to use it. You will do great with the posed shots, the rest is documentary. Hopefully they will have some diffused light for the ceremony. If not, try to overcome the sun with OCL and or reflectors. You will be fine.

Getting out of auto is sometimes frustrating and there is a need for patience. That's normal so don't get discouraged. In your photos you will notice that as you changed your aperture from f16 where everything is in focus (including the tape on the background) to 1.8. The background first becomes soft and then finally everything is soft. Also, as you changed your aperture from f16 to 1.8, you where allowing in more light. To keep the same exposure as the top photo, you need to increase your shutter speed or decrease your ISO. A great way to see what is happening is to do this: Set up exactly as you did above, same subject, background and lighting. Actually set it up in natural light and forget any flash for now. Set you camera to Aperture priority. Start at f16 and shoot as you did before changing only the aperture. Print each photo and type the camera settings next to each print. You will see the shutter speed change and or the ISO. Pick the print you like most, set you camera to manual, use the settings for that photo and shoot. Then decide if you want to soften the back ground more or less and play with the settings. Watch your in camera meter to keep it near "0". Using flash is another ballgame, you want to concur after you have manual down. Practice, practice practice and you will get it in no time.

Most tripods now have a monopod included. A lot of places will let you in with a monopod but not a tripod.

The 750 will out do any phone any time.

What do you charge for other shoots? Whatever it is, you dont want to make less than min wage when it comes down to the final #. Time + equipment+ business expenses+ taxes +your salary, added up should not be less than $min wage/hour.

Most photographers who shoot manual do not shoot to where the meter says is "0", they either shoot under or over. I shoot portraits and manual. If I shoot apt priority with someone with light colored clothes and a white back ground, the meter will be "0" and the background will be grey and the person underexposed. If I shoot manual and the meter reads "0" the background will be grey and the person underexposed. Most likely the setting will be the same as well in both these cases.
But if I set my apt, assume ISO is the same as the above scenarios, I will want to set my shutter or change my ISO to be about 2 stops over exposed, then my background will be white and the person perfectly exposed. Or I may want the background darker and light the subject. Or I may want everything a little underexposed. Just depends on the client, the light, the venue and the mood. I tell the camera what I want creatively not what may be technically correct.

you have got a lot of good suggestions here and I think you will do just fine. One other suggestion: for the formal bride and groom shots. If you can do off camera flash that would be awesome, add a light stand and a shoot through umbrella and you will be amazed at the lighting. Shooting outdoors in bright sun light can be very harsh. You may need 2 flashes to overcome the sun unless you can find some shade. A nice diffuser will help to block the sun if necessary. A 5 in 1 reflector may be good to get if you do not have one. All depends on the venue and where the sun will be. Gab an assistant to help you hold the light stand, diffuser, straighten out the gown and move hair away from the brides face so you can concentrate on shot. Good luck, relax and have fun. Oh make sure you have a place at the reception safe enough to charge batteries if you need to.

Go on You Tube and check out Gary Fong's videos for the a 6000, they are awesome.

I will be interesting to see what happens now with Nikon and Canon. Im not a sports photographer but I would love to play with this beast to see what it does.

I agree with the 750 considering what you do and where you are going. If you wanted mirroless, I would suggest the Sony 7RII if budge allows. If you are staying with Nikon then the 750 will be perfect.