Uma refeição tem comida
A meal has food
A meal is the foods prepared and consumed in a single dining activity.
Extra food not eaten at one meal may be stored and preserved for a subsequent meal.
A large meal may consist of many portions of many different foods.
A small meal may have small portions of food and few food items.
I'm also a learner so I can't tell for all of the words but I know that Portuguese has the guttural R (a.k.a. French R). It's like pronouncing h first before the r. You'll notice it in words that start with r and those that have double r's, thus in refeição, garrafa and cachorro. The rest is short normal rolling of the r (Spanish single r).
You're right. There are different ways of pronouncing the guttural R. In Portugal, you hear two main ones, the guttural one, which is a trill with the uvula, and the Spanish trill at the front of the mouth. In Brazil, you hear lots more variations: h, an h that's higher in the throat, some people even pronounce it like the ch in "nacht" in German. As long as you do it in the right environment (when r begins a word or where there are double r's), you'll be understood. Now, the rest is not really a short normal rolling of the r. It's more of a tap, almost exactly like the double d in the word "buddy" or the r in the Spanish word "quiero."