Hello. I'm kinda new to these mining and stuff. I've been using my Gaming GPU for mining and i can't say i'm making good money out of it. And lately i looked for mining products. I've seen products that work on 300-600 GH/s. So what i want to know is;

Can these miners work with scrypt mining programs, can i mine LTC and other altcoins?

After some research i found that most of the Butterfly Lab deliveries don't make it to the buyer so i turned to Avalon ASIC and a product named "Avalon2 – New 2U Size Machine" took my interest. It generates ~300 GH/s if i mine LTC with that the calculation sites say that i would earn approx 1000$/day ( considering these products works with scrypt ). Is that really possible? BTC pools gives 26$/day with that speed

And one more thing i couldn't understand is how does difficulty works. If i buy that machine will the difficulty ramp up because i have higher speeds or does difficulty applies to the general pool not depending on my hardware. Because i read somewhere that scrypt changes difficulty according to your mining speed ( considering these products works with scrypt ) so there won't be people earning too much money.

I don't wanna look like someone who doesn't work for something and just excepts the answers to just drop, because these questions are things i have to search ( and i did maybe not for a big extent ) but i wanna kno some specific things so i can understand what am i doing before going into all of these.

Thanks.