For the gear oil, get the small bottle, the rear only uses about 1/4 of a quart.
You can try bending the fork tube yourself but I would call around and price out having a shop do it as well, you don’t want to chip or gouge the chrome where the fork seals slide or you will be eating seals. The forks on the 225dx are a little small so having the tube bend is not that uncommon. When you pull off the shock you will have to remove the front axle and tire so you can do your brake job then too.
If you don't have a repair manual yet I would highly suggest buying on, the Clymer manual is my favorite and is well worth the $25 I usually see them for.
I have had mixed results with the trail pros, I say if they work for where you ride then keep them. They are a tuff tire they is very puncture resistant and they last forever. The biggest problem I have is they clog up in wet snow but I am guessing that won’t be a problem for you. Most of the time they were ok in the mud for me but sometimes the real sticky stuff would clog them up as well.
1984 Yamaha YT 60 Tri Zinger(current project)
1983 Yamaha YTM 200 (rear suspension kit)..... long term project
2004 BMW R1150R
1972 Honda CT 70
2007 Lifan 110