MTB newbie - advice on cost effective upgrades
I'm a novice when it comes to mountain bikes - spent most of my cycling years on road bikes - primarily vintage. I just bought a Performance M309 for my 10 yo son today for $40. I don't know much about these bikes or who Performance had make the frames other than it was made in Taiwan. Following their model numbers this would be a 1999 model but I couldn't find any specs on Bikepedia.
The bike has an aluminum frame that appears to weigh between 24-25 lbs - I was surprised by how light it feels. Other components (I suspect it's not all original)
Shimano Deore rear derailleur with 8 spd cassette
Shimano Acera front derailleur
Rock Shox Jett front suspension fork
Suntour MD300 triple crankset - 175 mm arms
It appears I need to true the wheels and put on new brake pads. The rear derailleur was acting up and tightening of the cables fixed that problem.
I've attached some photos and have some questions:
1) I have no experience with the style of brakes on the bike, although they seem to grab really well
2) I know Deore is a decent derailleur and I have some Tektro levers on a couple of vintage road bikes, but what about?
3) What about the rest of the components?
I don't want to spend a ton of money on it if I don't have to because my boys are notoriously hard on equipment. However, if there's something on the bike that I should realistically look at changing out now, what would that be.
Thanks ahead of time.