i understand that FI's parents are not obligated to throw the RD, but it is traditionally expected and we are doing a tradtional wedding. Meaning my parents are paying for the bulk of the wedding and therefore they are paying for FI's family's limos, guests' meals, invitations and all the tradtional stuff. Also meaning my bridesmaids are throwing my shower etc....all stuff that are not obligations, but inferred according to wedding tradtion/etiquette. FI's family knows this and did the same for their daughter when she married.
FI's parents have made no mention of RD or taken any initiative on anything..meaning no outward offerings to help, no card, phone call to me, bottle of wine, whatever--any sign of interest beyond the same old. For now, i'm going to assume it's because to them 5 mo's probably is a long time and they're probably right. (for me, i've been knee deep in planning so i have a pretty good idea of how long things take and how things can be unpleasant if left for the last minute, and in wedding time, the last 2-3 mo's is last minute). anyway, that's just me and if nothing happens after another month or so, I'll ask FI to gently ask them. i'm by no means saying they should send invites out 5 mo's in advance, but maybe just start looking around and making a reservation.
as for engagement parties and gifts...i can only speak for my expereinces in nyc and here, those who have engagement parties do often get gifts from their registries. people do bring smaller gifts/wine/champagne too, but usually don't come empty handed. i chose not to have an e-party, but it's pretty common. in fact a friend of mine is having her in-laws throw her a shower and she's been engaged 2 wks. and her registry has been complete since the day after engagement--not my style, but supposedly the norm among some circles.
for me, i was just talking about some symbolic engagement acknowledgement from immediate family (ie parents), or expression of interest.