RE: Another new boat LOL!!!
No need to buy a new pump. The brown ones are identical to the black ones no diffrence at all. It's a remarkable little pump you will not belive how easy they are to maintain. If you have any doubts about it performance just unscrew the four bolts and examine the little bits of silicone that make it work. As long and none of them are brittle you should be fine. Plus a rebuild kit from Tony is only like $12. Don't be surpised if you find some oil residue inside, that is normal. Just so you know the pump only works at idle, once the boat is up to speed the the water will flow thru the pump unabated.
I don't recognize the Tactic 2.4 just be aware that not all 2.4's work well on water. Lot's of threads here and elsewhere regarding radio's so I am not going to get into that here.
Yes you need (should) remove the flex shaft after each days use for two very important reasons.
1) To inspect the flex shaft
2) Moisture will work it's way into the windings and rust will start it's magic
The fitting is there to store a reserve of grease that will flow down the shaft with the heat that is created by the flex cable. Just an extra measure of saftey when your running a sport boat for long periods of time.
Get us some better pictures of the grease fitting and servo we may be able to help you further.
Leo