Congratulations on your longarm, you’re going to have fun! I have a Fusion and just bought prostitcher last year, but have not used it (my goal this year is to become proficient with it). As others have mentioned, join groups for help and inspiration, there are many on yahoo and Facebook. As far as upgrading to prostitcher premium, I think it would be worth your while, as if you have issues, you can still use the original version as well.
For threads and needles I buy from Superior Threads, IMHO you cant go wrong with them they know their stuff. As to thread choices, that’s up to you, buy some “try me packs” and play with them to see what works for you, mine only seems to like King Tut and I’ve given up on trying to get it to like other threads.
There are tons of things you can buy for your longarm, it can be overwhelming but do some research, play with your machine then when you’re really comfortable you will have a better idea what you need for you. Have fun!