Should I re-finance P&I to IO?

Hi Guy’s,Some advice needed,

1. Our old home is now our first IP. Original loan was of course P&I. Should I now re-finance as IO as there is no advantages in paying principal (Other than slowly increasing equity).

I am looking now for second IP and will be using equity in first IP for deposit ect, so does that require me to re-finance anyway for new amount?

2. With the current inflated market my little 3b 1b house is worth alot more than I paid. Should I be taking new loan now to take advantage of huge equity befor market starts to deflate? If so should that be a IO LOC?

3. Getting my moneies(lol) worth hehe. Does the bank accept an independant evaluation when working out worth of house and re-finance amout? Or do they insist on doing their own? Is it usually a fair amount?]

Thanks for any advice. I know it’s alot for one post but I have HEAPS of [?] that I need to ask.