Multi-sim for Unlimited Contact + Public IP

Hello

I’m thinking of getting the Unlimited Max contract for 69.99 eur, since there’s an o2 Antenna across the road and coverage is really good, so is speed, as far as I’ve seen with my partner’s phone.

I’d like to know whether is possible to add a Multi-Sim to this contract, afterwards, for my iPad, so I can ‘Share’ the data.

I’ve seen old threads saying it’s 10 eur more per month, plus 39.99 eur for the activation. Is this still accurate?

Also still accurate the 39.99 for having a Public IP?

I think clarifying these 2 would be important to conclude the contract online and port my Telekom line.

Thank you.