Each player is allowed to have 1 alt account on the server. Alts are allowed to play the game just like the main account, i.e. AFK farming, use them as a chunkloader, rank them up, bring them to events, collect rewards, etc.
Some vote sites allow for an account with the same IP to vote within their time limits and some don't. We have no control over that. Your alt can vote on any sites that allow it.
The only thing (that I'm aware of) that alts and mains cannot do for each other is pay tokens.