I think that it is far too easy to waste a lot of time on something like that. The GSM network and the GSM modules are there and they work. If you start to analyse them in a report, you are only going to get managers start asking themselves why you think it is necessary to ask the questions.
I assume that you have to use mobile communications of some sort, so you really don't have a choice what to use. You are using the network and modules as they are supposed to be used, so they are likely to work. If you are not careful, your analysis can get mission creep and you're going to try to justify 1% resistors, every single decoupling capacitor and the use of FR4 circuit board. If that happens, your report will be 10,000 pages and the project won't go anywhere.
In my experience with vehicle tracking devices, what matters is the protocol's ability to recover from data loss without the user seeing it.
Also the mobile network prices or contracts are what could destroy a project like that. In vehicle tracking, a very small amounts of data are sent by GPRS, so the minimum cost of a connection is the most important thing. Vodafone started by charging 1p, then they waived the minimum and let the data amount get up to 10 kB before taking 1p, then they "reduced" the price to 50 p per day. In fact, we found that the connections were 8p a time with a 50p per day limit.
The point is that they changed the prices by over 10 times, which is easily enough to make a project viable or not.
Different counties have different rules. PAYG in America has a $100 per year minimum.
What does is the project to do?