I can see how that a worry. I too forget where things are, but you won't have to worry about that. On the handset, the locations of items will come up telling you what aisle and area the items are. You'll get this explained, if you get the job. The handset will tell you everything from what to scan, which tote to put the items in and where the items are, so don't worry about locations.
The trolley is quite big. It's not a trolley like normal shoppers use, but one that holds eight totes. It can get quite heavy to push as you shop, so you have to be quite firm when you push.
After the shopping, it is the responsibility of the GA to sort out the van stuff, but different stores have different ways. I helped out with loading and unloading vans and such, but I also help out with stacking items on shelves after the shopping. I'm an evening shopper.