We have an attached tub drain stopper - the kind that you push down and it should seal and stay down to fill the tub. When I push it, however, it pops halfway back up, so I can't fill the tub. Any suggestions on how to fix it and keep it down and, therefore, sealed? Thank you in advance!

We bought an old house last summer and in the unfinished basement there is a toilet against the wall about four feet from a floor drain by the laundry area. The toilet works we just never use it and want to install a utility sink in it's place. There is a shower head arrangement above the floor drain that the previous owner used and we are going to remove that also so getting water supply for the sink is no problem. One question is if we install the sink in place of the toilet is there any venting concerns or should the sink work since it's just replacing an existing fixture? Also is there some kind of adapter that would connect the sink pvc drain pipe to the cast iron where the toilet was and does that old toilet flange come off? Thanks.