Can metal oxides react with water to form a hydroxide, then that with HCl to make a salt? Lets say I have a metal oxide and I put it in water, and it reacts. As far as I know, only metal oxides from group 1 and 2 react in water, making hydroxides.  

Now here is my question: If I add HCl to the hydroxide, can I be sure that it will make a salt and water? Or are my previous assumptions wrong?

An example that works would be Sodium Oxide which reacted with water and then with HCl produces NaCl and water. Does it work the same way with all metals from this group though?
tl;dr: Yes, depending on extent of reaction

The group 1 and (group 2) hydroxides for example: $\ce{NaOH,  KOH, RbOH, CsOH, Ba(OH)2, Ca(OH)2}$ are strong bases, being essentially fully ionized in aqueous solution; (although some are weaker $\ce{LiOH}$, $\ce{Mg(OH)2}$) . These should react with $\ce{HCl}$ - a strong acid forming water and a neutralisation product a typical corresponding salt $\ce{MCl}$ or $\ce{MCl2}$ .

Being soluble in aqueous envronment implies the salt is also obtained in this phase, so the question will be on extration method to use, in order to get this salt product in solid form.

Why I said depending on extent of reaction, is beacuse some metal oxides e.g $\ce{MgO}$ hardly form the hydroxide in the first place, and also insolubility with render the second reaction effectively out of question.