92 sanger Transmission fluid and engine oil?

Hey guys, I want to replace my transmission fluid but I am not sure what kind to replace it with? Pretty sure it is a velvet drive. also how many qts should it take, and how is the best way to check the level? on the trailer? in the water? hooked to the truck?

Also what kind of engine oil should I run? I have a 350 mercruiser. I think I ran a 40 weight last year thinking the heavy duty and only running in the heat would be good but just wondering what you guys run.

Also any tricks on replacing the oil filter? I didn't change it last year just the fluid cause I was lazy but I really need to get a new one Im sure. I just see a bunch of bloody knuckles in my future. FYI its a 92 sanger direct drive. Any help is appreciated.

It should be a Velvet Drive transmission so ATF fluid for it. You put in what you take out. I think mine is less than 2 quarts.
Run a multi grade with the last number at 40 weight for the engine. If you don't burn or leak oil then go with a synthetic. They handle heat better and are more efficient. If you go through oil you will go through more though, so use conventional if that's the case. I like a 5W-40 as used for many European cars nowadays. 15W-40 is just fine. I installed a remote filter adapter as it makes the oil changes much faster and less frustrating.
Brand makes some difference but not as much as the fact that you are putting in new oil. Check levels when hot, on the water.