How to conduct an interview for a Bitrix programmer?

Question

1C-Bitrix

I work in a company. There is a good knowledge of PHP, database. We were instructed to hire a Bitrix developer. I myself have never worked with Bitrix.
The project is so average in complexity - a website with a personal account and an API with CRM.
What should I ask him in an interview?
1) The site has certification, tests. Whether to ask for their presence, do they have weight, value, reflect the level of the developer?
2) There are different versions of the system, there is a framework. This is all the same, or it is understood that you can not know their framework and make a normal project.
3) Maybe you can tell me some question about the peculiarity of the system and its architecture (kernel, layer of work with the database) that can distinguish an experienced person from an inexperienced one?
4) Does it make sense to ask general questions about PHP, OOP?
5) Considering what the API will need to do, can you drive on understanding RESTfull?

Answer 1

1) In general, they have no weight, I have been developing on Bitrix for 4 years, I have not received a single certificate, but I have done projects that are quite large. Basically, these certificates are obtained to attract customers, and not to assess their knowledge.
2) Bitrix versions are different, yes, there are 2 kernels, the old kernel (like up to version 16) and the new d7 kernel, as far as I know the new kernel is great for writing your own modules and system components. Methods are supported in different versions of Bitrix. Without some kind of minimal knowledge, you cannot make a normal project, at least you need to know the base - this is working with elements, sections, what events are in the system, if you drop commerce, then you need to understand how the catalog of goods with SCU works. Maybe something else will be added in the comments.
3) At this point, information about the initialization of the component ( picture ) will be important knowledge .
4) Has, but only general questions, because in Bitrix work is mainly through api.
5) In general, if a person had no experience in writing a rest api, then it's okay, it's quite simple, I think in an hour of googling a person will understand everything if he is not a tree.