#3
1.) try one

2.) I have a 150 and I like it. A lot actually. The effects do sound somewhat digital (some more than others) but thats the comprimise for getting nearly infinite tweakability of what, 50 some factory presets (which imo suck). If you make your own you can get very useable tones.
#4
Not worth it. Many of the effects sound the same. I would go with just a smaller pedal, like the 150. You're going to have a could hundred effects that you're never going to use.