On the first round it looks +/- 20-20 for us and them.
So, at MP I would bid 2
♠ the first round - it will either push them to 3
♦, or I may go down 1 or 2, but -100 is generally a good score in MP, and 2
♠ is not going to be doubled (I am not sure they are going down in 2
♦ by the way, the opener may hold a decent hand). 3
♥ seems forcing, 16-20 and good hearts, so 3NT, but its a guess and 4
♥ may be just as good of a contract or better.
I am just describing my hand at this point because partner took control and hope for the best ....... I am not convinced my stopper is a double stopper and in 3NT there are no entrances to my hand to make finesses, so it is not going to be an easy contract unless partner has running suit.
At IMP pass the first round (the ops are less likely to compte for partscore, and it is not as important. Also, if partner happens to have a good hand, I dont want him to get excited, as he will be pushing for games). After 2
♥, assuming partner is 18-20 and you are allowed to pass with lousy hand, I will start with 2NT the second which is exactly my hand - I dont think p will pass 2NT - I just want to let him bid again, if he has extra hearts or 4 spades - may be 4major would be better. If partner passes 2NT or signs off in 3
♥ in IMP NV vs vul he knows what he is doing and we probably shouldn't be any higher.....