Hi and welcome to Healing Well, even if I'm a bit late at doing so!
I'm not quincy, but I can answer your questions about rectal meds. They're pretty much what their name implies...medications that are "taken" through the rectum instead of through the mouth! quincy and I both use mesalamine enemas (essentially, a liquid version of the Lialda he already uses that you shoot up the bum, so to speak). The reason to use them is that the oral meds often don't do such a great job at treating the distal part of the colon, and the enemas do that very effectively. Studies show that people who use mesalamine enemas twice weekly in addition to oral meds stay in remission for longer than those who only use oral meds. I find that it's not a big deal to use them twice a week, if it means I stay in remission for longer!
I'm also not callalily, but I can answer your question about probiotics, too. They're basically the "good" gut bacteria. One of the theories behind UC is that we have an inbalance of gut bacteria...too many of the bad guys and not enough of the good guys. My personal opinion of a "high-quality" probiotic is on that has several different species (mine has about 8 or so different species of Lactobacillus and Bifidiobacterium), is refrigerated, and has at least 10 billion active cells per capsule.