No, there are no advantages to staying onsite when it comes to parties other than resort guests are allowed to purchase tickets earlier than offsite guests. This is no longer in effect for 2024
MNSSHP as party tickets are on sale for all guests.
For
MVMCP tickets will go on sale for resort guests first then offsite guests later. (Can't remember actual number of days.) Historically parties do not sell out prior to being offered to all guests so other than waiting, there should be no difference.
ILL$: No, a guest cannot purchase an ILL$ with only a party ticket. They could in the past but stopped this practice.
VQ: There should be a 6PM VQ drop for all guests holding a party ticket for that night. Guests do not need to have scanned into the party to be eligible to try to join a VQ.