Hi yukime
traditionally yes u must step into groom house to represent 过门 (meaning you are married into his family).
but this is a tradition. if all are ok to treat hotel as groom house, there is no negative impact. most MIL will want this step to be performed at their house, rather than hotel...
Hi LightHouse
some of the general good dates are
6/9, 13/9, 12/10, 24/10
Also, is it true that if we have alot of Water elements in our bazi, we should avoid the "winter" period?
no such thing