If I do not have any money to buy a house, will this group still be beneficial?

Absolutely, you will see a benefit. Whether or not you have the finances in place or planning on buying this year or in a few years, being a part of the Mastermind group would definitely help you. This is the time that

Can my partner attend?

Yes, your partner / significant other can sit in on the conversation and participate, if they want.

Do I have to attend every single meeting?

No, but the more times you come, the better. The benefit of attending every single meeting, is that we will have a different experts available. Attending every meeting will also allow you to build a stronger relationship with the other participants.