Hi lance-
Welcome to this fantastic site. My husband Joe is the patient here and he's had 3 valve surgeries. So it was echocardiogram, angiogram (catheterization) and TEE multiple times for him.
The echo is non-invasive, not a problem at all. The TEE is a small transducer down you throat, you'll be groggy and they will spray your throat with a numbing agent. Joe's had several catheterizations, in his arm, in his neck, up the groin (the usual). He doesn't ever complain about them. The doctors who do them really know what they're doing and it only takes about 45 minutes. Some people are in a very relaxed state, and some even watch the procedure to see their hearts in motion. The dye is warm when it goes into your blood system. The worst part is lying still after the procedure. that is to allow the catheter site to clot up. But really not a painful test.
All of these tests are very necessary. You wouldn't want your surgeon cutting you open without the very best information, would you? The more info they can get beforehand, the easier the surgery will be and the better the result will be.
Just think of all the people here who have had these tests. They'll be wth you in spirit the whole way, through the testing phase through the surgery and after when you are recovering.
You will do just fine.
Remember, surgeon knowledge = good results.
best wishes.