Unfortunately, there's no alternative ISPs that piggy-back over Comcast's cable anymore. Your only alternative is going with some form of DSL...
Speaking of, are you in AT&T U-verse territory? If so, give
TOAST.net a look. 6Mbps vDSL for $38/month, $50 install, simple terms of service, good support department, only a 12 month contract, no modem rental fees despite having to use their modem/router combo, no price increases after going month to month.
6Mbps is plenty for streaming, though right at the edge of full HD quality for a single stream (you really don't need HD video). That said, an extra $6/month with TOAST will double the speed, though.
As for WiFi access, the provided equipment will have an integrated router and WiFi hotspot. Most of them aren't great (blame AT&T for this, not TOAST.net) but are usable. They can be a hassle to properly bypass to use your own equipment if you don't know how to do networking, but it's not impossible. If you use VoIP services, you'll definitely want to put their equipment into bypass mode and use your own router.
As for your three questions:
1) WiFi reliability depends more on local interference and the channels you select for the network more than anything else. As for a rate to pay for home internet, the going national rate these days is creeping up. $50 is sadly considered the low end anymore. (TOAST is a bargain if you can get it.) It's worse if you're in a monopoly region, especially Comcast.
2) Bundling is never a bargain anyway, so I'd never recommend it in the first place. It's a sucker's game... but you'll find that Comcast games things to where internet bundled with basic television will usually give you the cheapest prices. It's absurd.
3) Monopoly ISPs with no competition and terrible customer service are really putting the screws down these days. Try to be polite and prepared with the patience of Methuselah, but also be prepared to cancel and lose service. If you play chicken and don't blink and you get the right agent, you might be lucky to save a couple bucks. It's a hard path. Good luck!