well basically do limited edition pets come out randomally or on a special day, and whatdifferent ways are there to earn money?

Limited Pets are released randomly but it's a rare event so Elixirs are the best choice if you want to get one of them.

And for making money there are numerous way, the most popular is probably doing quests like Wizard, Item Hunt or Saggitarius, then restocking, buying things from the Cash Shop for real money to sell them here for sP, Stock Market...many ways as I said. XD

I see, It just that It's kind of hard when you don't have enough money to do such things, I like Randm, It's so easy :)

Random is good, play it as often as you can. Once you make a little sP from that and selling whatever you can get your hands on, Wizard Quests are a very good way to make sP. You can either sell the tokens you get, or use them in the vending machines and sell the items from there. Also, restocking really isn't very hard, buying items from main Subeta shops and selling them for profit in your own shop. Use Shop Search to price your items lowest.