Doubts regarding Future Trading

Hey,

I have some questions regarding Future Trading, Kindly help me out.

1. Can I keep my Long position open for 6 months?

a) If yes, how much fees will be charged extra?

b) If no, what’s the maximum limit of days to keep the trade open?

1. Can the liquidity price change itself?

2. Imagine I have a trade going on worth $1000 and liquidity price is $1200 on ETH, what if I add $1000 more at lower price, will my liquidity go down aswell?

Thanks for answering ????