Recently thrifted a used bike that seemed in decent overall shape but definitely a fixer upper. Have wanted to get into riding for a while, and seemed like a good way to do so, plus needing to get it into workable shape means I'll "be forced" to learn how to maintain it.

Is the first bike I've had as an adult, and first that has obviously needed any TLC. Am mostly asking for advice/suggestions on where might be a good place to look to get guidance on this sorta thing. I can google and search various subs all I want, but without knowing specifically what problem I'm trying to solve, I'll just end up in the weeds repeatedly. Am in the south portion of the city, but regularly end up right near freeride, would they offer something fitting here? I love to learn, but guidance and some level of instruction would be fantastic.

From what I can work out, is a 2010s(2016?) Schwinn Fairhaven with 7-speed shimano.

• Front brakes seem fine, sans slight rubbing which am not sure if is from sliightly out of true wheel or very poorly adjusted centering.

• Rear brakes non-functional. Cable pulls from the lever and seems very stuck/difficult to slide. I assume replacing the cable would solve this? Have tried redoing the cable attachment at the brake end to no avail.

• Less guaranteed issue and more so curiosity: Is shifting to higher gears supposed to be very easy, and down to 1 supposed to require quite sizable force? When I'd picked it up, was resting at 7. and was worried I was going to break something originally. Have since managed to get it back to 1 (largest) but want to make sure I don't have something under horrid tension that it shouldn't be.

• Any recommended "cheap" tool kit it start out? Have been able to scavenge one or two tools to start with (hex keys mainly) but would a $20 walmart or amazon special be acceptable to grab just to start? Buy once cry once is the ideal, but so is "can work up to".

• Aaany other suggestions/tips/things to buy? Helmet n such sure, but no ideas on what to look for there or locks either. That and oil/grease pointers

tl;dr New (used/fixer upper) bike owner, hoping for some direction/guidance.

If this sorta thread isn't allowed, I do apologize.