The timing belt can't squeel. It has teeth, if it does any slipping too you'll know it because if you're lucky the car will run like garbage and if you're not you'd have heard a couple loud thumps and it won't start ever again after that.
Also, if the tensioner is leaking... well, see above, plus the tensioner is only the size of a finger. It can't have much more than a tablespoon of oil in it total.
The squeeling will be the other belts. Even though you don't have a fan belt there is an accessory belt, A/C belt and power steering belt. One of them is doing it. If it only started recently if could be A/C because it'll come on with the defroster setting that you probably just recently started using.
How's the blow-by? I'd say you have a leaking either form the dipstick popping out, the oil cap leaking or something like the front main leaking and slinging opl of the pulleys. But the front main, or the cam seals should get oil all over the t belt too.
