Since you use well water, do you know if you have metals in your water? If not, you might want to get the water testing before you take the chlorine too high.

You can use muriatic acid in a vinyl pool. To lower alk, the process is to add muriatic acid which will lower your ph and your alkalinity. (Don't let the ph go below 7.0 however.) Then, you aerate the water to raise the ph back up without the alk going up. You can turn your return jet facing upwards to create bubbling on the surface, or throw in a gaggle of 12 year old kids to splash around. Anything you can do to aerate the water. After the ph gets up to 7.6-7.8, you repeat the process if the alk wasn't lowered enough the first cycle. Repeat as many times as necessary.

Regarding whether or not you will need stabilizer, not sure. Wait and see. Give it some time and see if you have trouble keeping a chlorine reading through the day. You can always add cya (stabilizer) later if you find that you need it.

Any more questions -- ask away. We are here to help. Glad to have you on our forum!