How far do you go for contact with a birth family and what is acceptable for visits?

We are being considered by a birth family to adopt their 1 1/2 year old child. The birth father has not asked us directly for weekly visit, but has indicated that is what he would like. The bio grandparents would also like visits, and the foster care provider. We have stated that we are open to contact and that it is a given that they would be invited to all sporting events, plays, musicals, ect. We also offered every other month visits with pictures and letters in between. The grandparents have said they would like to babysit, have sleepovers, and take him on outings. We are fine with working out those specific details. We are having a problem with allowing the foster care provider to visit and are unsure if all these people will want individual time or joint visits. We have also discussed with the grandparents that we have no problem with this child calling them grandma and grandps. We also think it may be too much contact in the beginning, where the birth father and the foster care provider feel there will be a lot of visits in the beginning. Not sure where to go from here, any suggestions