Quick questions

I want to make sure I don't offend anyone at mass or anything so I had some questions

1. I know when you enter the sanctuary, you get the holy water and make the sign of the cross then genuflect before sitting. But do you have to make the sign of the cross again while genuflecting?

2. I'm not able to receive the Eucharist yet so what do I do while everyone else is receiving it? Do I remain kneeling or just sit back down normally?

3. I did go in the communion line during Easter and crossed my arms for the priest to give me a blessing instead of the Eucharist. However, he specifically invited peoole to do so if they couldn't receive the Eucharist so everyone could go up that time. Are people who cannot receive the Eucharist being able to join the communion line and receive a blessing by crossing their arms something that I can do during any mass or it reserved for special ocassions?

Thank you!!