Reversing the polarity wont damage your guitar or amp, it would make the sound from the guitar a bit thin and nasally, Lots of players prefer a reversed polarity pickup, most pickups come with a good set of installation instructions so there’s little chance of mucking it up.
Invest in a soldering iron and have a go.

Hi!
Careful at the polarity of the pick-up!
If you invert the cables you will have a out-phase sound.
This side-effect can be a defect or not.

It’s very easy to change pickups, from memory that guitar has a full sized humbucker on the bridge and a single coil on the neck?, take off the strings, then the scratchplate and make a detailed drawing of where the wires go to which positions. unsolder the pickup wires and remove the pickups.
Buy your replacemet pickups and solder them to the same terminals you unsoldered the old ones from, if you get problems come back here, most pickups have 2 or 3 wires, buy whatever pickups you need and come back for more advice.