lots of questions!!

[im tha best]

i have a lot of questions that arent really related to each other in any kinda of way but here i go...

1. i have a bad whine in first gear of my tranny (three speed) and i've replaced my gear oil last week and i thought that would help but it didnt inprove any, so i was wondering what i would have to do to make it stop. Rebuild it or what? and how much would you think i would have to spend on it? Also, it was converted from col. shift to floor shift and sometimes the shift rod either gets stuck and i cant move the shifter unless i almost break it and sometimes it just comes out of the clutch linkage altogether and leaves it in whatever gear it was in and just flops around without doing anything. then i have to get under the truck with a screwdriver and pop it back into place. how would i fix that problem?

2. How would i go about fixing my heater? it blows, not hot but not cold, air. its cold enough not to be a heater and its warm enough not to be AC. So how would i fix it so i can have heat and not freeze all winter long?

3. what gears could i put in my rear end to make it a little quicker without losing alot of mpg on the highway?

just to throw this in there, i put some thrush glass packs on it the other day and now it sounds so mean that sometimes i forget its a little sixbanger. i'll try and put a video and a picture of my exhaust up a little later.

thanks for the help!