No. You will have to provide documents confirming the ownership of a property and amount of funds.
INVITATION
The length of the invitation depends on the amount of funds you have to cover the costs of accommodation for a foreigner and the costs of the invited foreigner's return trip to his/her place of origin or residence or his/her transit to a third country that will permit the entry, equal to the price of the ticket to this country.
Invitation can be issued for up to one year period. The period of the invitation depends on how long you can provide accommodation for the foreigner and on the amount of your funds.
No. Invitation is a documents that might be needed during visa procedure at the Polish consulate and only for tourist purpose. If you want to work in Poland, your employer should apply for work permit or register a declaration on entrusting work to a foreigner. If you are in Poland, you can apply for temporary residence and work permit.
No. Invitation is a documents that might be needed during visa procedure at the Polish consulate. If you are granted a visa, you will be allowed to cross the border.
No, you need an invitation only while applying for visa in order to come to Poland. If you are already in Poland and you would like to extend your stay you should apply for a visa extention or temporary residence permit.
Yes, but only if they have been staying in Poland directly before the issuance of the invitation legally and continuously for the period of 5 years or were granted a permanent residence permit or a residence permit for a long-term resident of the EU.