How common is freebasing and throat infections: sore throat, hoarse voice, tonsillitis???

First of all, what do you mean by "freebasing."

That's an old term that used to be applied to cocaine users before the advent of crack.

I suppose there are some meth users who use the term, but they are quite rare.

Smoking meth isn't really smoke anyhow. It is meth fumes. Pot is smoked, there's a flame and the organic matter, cannibas burns and produces smoke - real smoke.
Meth and crack are not smoked, but the drug is heated to a state where is becomes fumes and the fumes are inhaled through a glass tube or other device.

The incidence of throat, sinus, tonsil and larynx infection or irritation might be slightly higher than the general population.
But I don't think it is significantly higher.

Why do you ask?

Oh I just ask, b/c I've already got a long list of suspicions that have me wondering if a friend is using, whether it be meth or cocaine. Aside from this recent "throat infection" said friend has come down with, I've also noticed dilated pupils, incessant jabbering, money issues and irratic, unreliable behavior within the last month. Yet, I've never seen said friend partake in the activity, nor any paraphanalia lying around. So, now I'm on a Sherlock Holmes kick (I've already asked, and they denied they were using). I was just wondered if snorting or smoking could lead to various throat ailments bad enough to lead them to seek help from a physician? Seems like they were sick with a cold a month ago, and now have another one? Have any former users here had this experience??

(I guess "free basing" is a rather outdated term. It brings up images of somebody sitting outside of a disco in their car, freebasing with their friends in the late-70s (lol).)

This is your question:
"just wondered if snorting or smoking could lead to various throat ailments bad enough to lead them to seek help from a physician?"

and the answer is "YES"

it could, that doesn't always mean that it will, but it could.
The other things you listed are also among the common characteristics and behaviors of a meth user.

Common signs of meth use:
1. Lack of sleep,
2. Lack of appetite,
3. Nervous twitching,
4. Blaming others,
5. Grinding teeth,
6. Clenching jaw,
7. Seldom smile,
8. Avoid family and normal friends,
9. Unable to be responsible,
10. Dental and skin health gets worse,
11. Abnormally high amounts of energy,
12. Paranoia,
13. Obsessive perverse sexual behavior,
14. Enlarged pupils,
15. Tweaking.

also,using meth lowers the immune system .. so the user is more prone to colds,flu etc

Snorting meth was always harder on my throat than smoking it was. The rest of what you have described could be meth use. Hard to say.

The first time I smoked crack I got ulcers (not blisters) in my mouth and throat. The doc on campus hadn't been informed of that activity, so he thought it was just a viral infection. He was surprised I had never gotten it before, and said that I'd get it again. I was so sick, and my hip bones were really aching.

Regarding meth, once the four of us all got blisters (not ulcers) in our throat and mouths... allegedly from vaporizing a particular batch of meth off tinfoil.

Ouch! good times, good times!!