On 1C-Bitrix, goods are added to the basket one at a time?

Question

1C-Bitrix

Hello ! I immediately ask you not to beat me)
In general, the problem, as you read in the question, is the following: there is a ready-made site (not made by me). In Bitrix, I am a complete 0. I don’t have much time to understand its structure. But he contracted to help a friend (he has his own company, and there is a site made on Bitrix). I myself am not bad at php js and other related goodies.
1. We select a product, set the quantity, click add to cart, and there is 1 pc in the cart, regardless of how many pieces were delivered.
2. Installed the "Mobile version of the online store" module. Everything works fine, but there is one problem... the catalog itself is divided into regions and, accordingly, the orders themselves come to different regions. When we open the site from desktop devices, the geoip module opens (whose settings I can’t find in the admin panel, if they should be there at all) and the city is selected, then the redirect and everything is fine. But when we open the site from a mobile device, it asks if we want to open the mobile version of the site, and if we agree, then we get into the Novosibirsk directory (actually, we need a mobile version only for Novosibirsk, for other cities it is not necessary), and if we do the same while being anywhere in the world, respectively, we still get to Novosibirsk,
3. When we make an order without registration, it works clumsily, you enter the data and he says that he sent a letter with account information to the mail, (the letter does not come) and does not go anywhere else, the order is not processed.
I understand that without seeing the original when you can hardly help. But at least put on the right path, what to read, at a minimum about Bitrix and its structure, in order to solve these problems.

Answer 1

1. Check in the firebug / inspector whether the number of goods is passed in the parameters, also in the component settings, the name of the variable in which the number of goods is passed must match the variable that is actually used in the get request.
2 and 3. contact the developer who implemented the project, you can guess what the problem is for a long time and to no avail.