I often get a little pinkish/bloodyish discharge after sex. My midwives told me not to worry, that I have a 'friable' cervix. It's not being damaged, and as long as it's my only 'symptom' then they have no worries.
Pelvic floor wise, I went to a Pelvic Health physical therapist after my first and it really helped--I feel like I'm backtracking during the pregnancy though--Go Team Incontinence! She gave me exercises to do, and measured my strength/endurance with a probe. We worked on not only the floor, but making sure the whole system was working together. I had a really strong pelvic floor pre-baby, but was seriously deficient with the other surrounding muscles, which is likely why I ended up having some post-birth issues.
Check out Katy Bowman's advice. http://www.alignedandwell.com/?s=birth&option=com_wordpress&Itemid=223
She does biomechanics and is one of the people behind the new Squat! Squat! Squat! advice. Squats do more for the whole system than Kegels, and if you have damage kegels can strengthen parts of your pelvis at the expense of others and actually compound the damage (according to the things I've read anyway, I'm no PT/RN/MD!). My PT gave me a 'zip it up' exercise to work the muscle between your tummy and your pelvis. She describes it as the feeling you get when you try to squeeze into tight jeans, and showed me how to press on my pelvis while doing it to see how deep that muscle goes. It's been pretty helpful.