The investment industry is a huge field and it would help if you could be a bit more specific as to what your are looking for. It can be analyst or a trader.
1.What are the job titles for entry level position in
investment ( for example for job search)?
Depending on what your wants to go into....an entry level position can be an administrative one (e.g. portfolio administrator), research related (e.g. research associate), or a customer service rep, or an assistant trader etc.
2. List of mandatory knowledge and certification for
starting (minimum to be hired) and some desired knowledge ( nice to have):
Employers generally look for, at a minimum, an undergraduate degree (preferably business-related). Increasingly, many are asking for a CFA charter. If your you are interested in becoming a research analyst, he most definitely would need to either have a CFA or be enrolled (or willing to be enrolled) in the CFA program. Additionally, many employers look for successful completion of CSI courses (required by the regulators for a lot of investment-related jobs in order to conduct business in the province). The most common CSI courses are the CSC (Canadian Securities Course) and the CPH (Canadian Practices Handbook). CSI courses are fairly easy (can be done in a month or so with some effort). Some employers might be willing to hire your friend without the CSI courses as long as he completes them in a timely manner after being hired. That was the case with me.
3. Books recommended for reading:
There is such a vast array of books available on the subject that I honestly don't know where to start. Start with the basics so he can familiarize with the industry lingo, e.g. P/E ratios, ROEs, dividend yields, etc. (I assume your knowledge is minimal). Then move up. Again, the CSC course covers all of that, so you might consider looking into taking it, particularly as it is a regulatory requirement for a lot of jobs. Also, it might help to start reading investment-related or business publications, e.g. Bloomberg Markets, as well as being on top of what's going on in the business world (reading daily business publications such as Financial Post or Report on Business should take care of that).