John,
Before you read this, remember this is just my experience and I'm a finance person, not a doctor!!
I had surgery on my mid-tongue on Thursday, 3/25/04, with 1 CM clean margin (early stage II). The largest piece was removed just beyond the tip. Looking over my records, I didn't take pain meds on Thursday or Friday. The worst pain was Sat and Sun. This is because of the steroids given. I had different ones for the intial excision on 2/27/04 (removed majority of tumor - they didn't know it was cancer), and the more difficult pain then was day 1 and 2.
I kept a bilateral facial ice pack around my face the entire time (highly recommend it) and tried/failed sucking on ice chips. I started drinking water and eating soup late Friday. I was sick of Ensures, jello, soup, etc. by the following Thursday and took 1 hour to eat 1 piece of pizza (cut up very small). I also gave in and ate a "Grab size" bag of Doritos over a couple hours.
I remember my tongue getting physically tired from trying to eat and talk. It's a muscle like many other parts of your body; it's trying to re-heal and re-learn how to work.
I highly recommend meeting with a nutritionist. I met with mine today, through the hospital, and I wish I'd met her before the surgery. She gave me a daily calorie and protein, which is higher than normal to help your body recoup, and a more in-depth explanation why. To reduce the amount of food intake, she gave me high cal/nutritional and low volume smoothie recipes. While this is due to the radiation side effects (hurts to eat/swallow/brush teeth after), it would have been awesome the first 1.5 weeks following surgery.
My speech improved dramatically each day, and continues to do so. However, radiation is setting me back. My husband says when I'm mad, my speech is perfect

. Your speech recovery will depend on the removal place of the tumor (tip of the tongue is used to articulate, so that may take longer to re-learn), how deep, if any nerves are removed (no major ones for me), amount of swelling etc. Your doctor may have a prior patient willing to speak to you that experienced the same placement/stage of tumor, and you can listen to their speech 1 month, 1 year, 5 years down the road (I listed to a woman who'd done it 15 years prior).
My voice changed for about a week from the swelling, but returned to normal afterward.
As for survival rates, I had the same inital reaction as you and it freaked me out. However, medicine takes huge advancements every year. Those studies are from a different time, even though it may only be from 5 years ago. The marjority of tongue cancers are caught in Stage III and IV, which I assume skews the studies. These are treated much differently and have different outcomes from Stage I. I've read many posting and met many people that had Stage IV and kicked cancer's rear-end! Ignore the studies and blaze your own trail!
If you're anxiety level is up, you may want to discuss radiation or bracheytherapy with your doctor. However, I don't believe it's recommended for Stage I. Ask your doctors a zillion questions and don't be afraid of second opinions. Radiation couldn't start for 3 weeks after my surgery (many times it's 4+ weeks), so you have time to discuss it. I have all my questions written out from my visits, and would be happy to email the list to you for ideas. Just let me know!
Sabrina