second hand kit

Hi, since setting up my first tank I have now become something of a magnet for other people's old kit! :lol: Actually, I am very happy because I am really looking forward to setting up some more tanks.

What would you do with any of the following items:

20 gallon tank - goes without saying, I'm going to set this one up. I'm thinking about a totally different set up from my other one, for different species. The other one's ended up being hill-stream for my panda gara. So this will be for more static water lovers, or something requiring a more delicate balance of pH, or softer water. Recommendations?

8 gallon tank (I'm thinking ideal for fry, QT, and whatever - or maybe for a betta? - I'd love a betta!)

Second hand substrate. The tanks have be disused for several months, but the substrate was still wet. Is it worth keeping, or not worth the risk of harbouring something nasty? Its somewhere between very fine gravel and very coarse sand.

An old ornament. Assuming it cleans up ok, and there's no damage (and I do like it) I presume its ok to reuse. Any danger signs to watch out for?

2 old heaters - I've not tested them, but assuming they are working ok is there any reason not to keep a heater (iro 20yo at a guess)? Has the technology changed massively?

A bunch of meds - for the bin, right? I've rather have new, reliable, known stuff.

broad spectrum pH test - gave the same result as the the API master kit. Might as well keep this I guess. Plus it's range is 5-10, so great if I'm not already vaguely sure of the pH.

6.5 buffer - absolutely no idea of the age - does this stuff degrade?