Either or will stabilize fuel. I use seafoam due to the added benefits of it's cleaning abilities. Once I start er up in the spring she gets a cleaning too.
Bad idea. Doing that accelerates wear. A dry start twice a month and not riding it doesn't let it get hot enough to expand the pistons which let's raw fuel mix with oil and condensation build up.
This is very bad advice.
+1. Pretty well documented out there that you do NOT want to start your machines and just let 'em idle for a bit. Treat 'em right before putting them to bed during the winter, get the battery on a tender and then just leave 'em be!