I've had my tongue pierced for over 7 years now and I have had no problems what-so-ever and I don't plan on giving up my piercing any time soon.
When I first had it done I was swollen for a good week and lived off of liquids. Ice cream, popsicles, ice chips are your best friends! The swelling is different for everyone. Some are only swollen for a couple days, others like me, a bit longer.
It's the swelling the affects your speech, not the piercing itself. You will not talk funny once the swelling goes down. I talk just as normally now as I did before the piercing. The swelling is also not that bad that it will affect your breathing. I mean, it will not cause your tongue to swell up like a balloon.
Like I said, I have had no problems. I did not get sick from it however there have been cases of tongue piercings causing serious health problems. This doesn't happen to everyone, actually very few people have had anything serious happen from their piercing but I would google it so you are aware of the potential risks.
I went to a reputable piercer and followed all the after care instructions to a 't'. Do not however use listerine or any kind of mouth wash. Listerine especially contains alcohol which is too harsh for any piercing and only prolongs the healing. Instead, use a sea salt solution. Dillute 1/4 teaspoon sea salt in 8 ounces of water. Rinse for about 15-20 seconds after every meal, drinking anything but water, smoking, putting any foreign object (fingers, pens etc) in your mouth. Do this for 3-6 weeks. You also want to be careful that you do not over clean your piercing. Signs of this is a very white or yellow looking tongue.
Another thing to be aware of is the initial piece of jewelry used during the healing period is much larger than you would normally use. This is to accommodate the swelling. This makes it very easy to accidently "chomp" down on it and chip a tooth. There are more dental problems associated with tongue piercings than anything. This is due to incorrect jewelry size. When you are able to downsize the jewelry, usually 6-8 weeks, you shouldn't have any problems with this.
You may need to try a variety of different post lengths to find the one that's best for you. Once you find the correct length you can use the steel balls but acrylic is much easier on the teeth if you do happen to accidentally bite down on it.
One more thing. Regularly check that the beads are on tight! I have swallowed a couple beads before.