My torch is a Harris model 85, from the tiny kit I bought off CL, it is like new, 3 tips #1,3&5 plus a cutting torch.
I have a great guy at a local welding shop only a mile from home. He already exchanged my acetylene tank, cost was $30... I actually have 2 oxy and 2 acetylene tiny tanks so can be prepared for them to run out.
if I do find other tanks to buy I can run it past him to be sure they can be exchanged.. just watching daily for a killer deal, will focus on the 40cfm like you advise.
I don't have flash back arresters, do I need them?
It's best and smart to have them. Same with at least one fire extinguisher and a back-up hose or container of water right there- not across the yard. Cheaper than losing your shop/house. Things go wrong fast. Sounds like you're in good shape with tanks right now. Very cool.
Not trying to overwhelm you- it's easy to succeed, fail and collect gear & info for 20 yrs and then say "get this instead of that." to the next guy. Pre Internet, I didn't have succinct good advice getting started. Gas welding aluminum and such was voodoo. Nearly everyone said get a TIG or a cheap MIG with aluminum spool gun and forget about gas welding. My only goal is to help others waste less money and time than I have. It doesn't matter who laughs at me. Unkes it's thick metal, I hardly ever use my TIG or stick. Gas welding is my go-to method.
Use what you have, Practice a lot (& then practice more) and plan towards better gear to purchase once IF you need it. If you already have a Harris torch, your tips may fit one of those craftsman gas-saver type handles with thumbwheel on-off. Do some internet searching. If you're not cutting a lot and welding small/thin, a Meco midget is the way to go imho because it isn't likely to be phased out soon. I added a couple of link above. Kent White is a renowned expert and significant resource for serious gas welding.
Practice of proper method is the most significant part of being a good welder. No book or video will practice for you. If you're good, you're good even if the gear is less than optimal. People gas weld thin aluminum with a plain cutting torch, usually just to show it can be done.
