Tier 2 (General) Dependent

[DayZero]

Hello,

I would appreciate if someone could advise me on my case of applying for a Tier 2 (General) Dependent for my girlfriend (possibly wife in future). I have moved to London under Tier 2 (General) Migrant in the beginning of February 2016 and now would like my girlfriend to join me living here for the duration of my visa (5 years). We are initially looking into her applying as an unmarried partner, however if we realise that is not a viable option, we consider marrying and would like to understand what is the best approach to this situation.

Here's the situation background:

I met my girlfriend in the summer of 2014 in Moscow. Before that we've been talking on an instant messenger platform. We started living in my apartment in Moscow in September 2014 and moved into her apartment in Moscow in the beginning of January 2015. In August 2015 I received an offer from my employer to transfer to London office and applied for and in December 2015 received a 5 year Tier 2 (General) Migrant (points-based system) visa valid from 1st of February 2016. I applied alone. We continued to live together in Moscow until end of January 2016 when I moved to the UK. Throughout this time we had done several trips for vacations together. My girlfriend has a business in another city in Russia and works remotely. She used to be in another marriage and has divorced in August 2015, although her relationships with her ex-husband have de facto ended long before she met me.
I moved to London on 24 January 2016 and my girlfriend has applied for and received a visitor visa for 6 months. She came to visit me from 3 March to 11 April and stayed with me in my house. She came again on 16 April.
I would like my girlfriend to stay with me for the duration of my 5 year visa as a dependent.
In terms of documents that support our application (specifically that prove our relationships):
• We have got lots of photos from the trips
• We have got other photos with my family
• We have got most of the electronic communication (messages)
• The concept of joint accounts and joint bills doesn't exist in Russia, I believe, so we don't have them
• We have got a rental agreement with both our names for the flat in Moscow
• We have got a rental agreement with both our names for the room that I'm renting in London beginning with 1 February 2016
• We have got hotel bookings and flight tickets receipts with both our names on it

Could you advise whether applying for an unmarried partner is viable option in this case? Would you be willing to provide assistance with this application?
Does the fact that she has visited me and we lived together count towards or against our application (as unmarried partner)? Do the days spent together in the UK with her being on a visit visa count towards the 2 years of living together required for the unmarried partner visa?

Otherwise, I understand that our best option is to get married, could you please explain more on this? Is it better to get married in Russia or in the UK and what difference would it make? If we are to get married in the UK, is it okay to do it if my girlfriend currently has a 6 months visit visa with an intention to apply for a dependent visa afterwards? Will she have to apply from Russia or can she apply in London? Will she have to wait until her 6 months visit visa expires or can she switch to the Tier 2 General Dependent without waiting?
Is it okay for her to visit me for extended periods under visit visa? It's valid for 6 months, does that mean that she can stay for the period of 6 months? Can she stay for 6 consecutive period of 1 month? What would be the consequences of this? What are the limitations of this visa in terms of number and duration of visits?

I realise that it's a lot of questions so to summarise the most important question is: what is the best approach we should take in this situation?
Thank you very much in advance.

[Casa]

An unmarried partner visa requires documented evidence of a relationship 'akin to marriage' and includes the mandatory 2 years of co-habitation. The Entry Clearance Officer would expect to see joint commitments, such as shared finances etc. It appears from your post that even if you had continued you live with your girlfriend, you wouldn't have reached the crucial 24 month mark until some time in September 16.
Now that you are living in the UK, short visits won't be sufficient to maintain the co-habitation as a visitor visa is exactly what is says on the tin...for visiting, not for living. You also have the additional issue that your girlfriend is not permitted to spend more time in the UK in a 12 month rolling period than she is spending in her normal country of residence. If the Immigration Officer feels that she is spending too much time here he could refuse her entry.
Under the present situation, you won't clock up sufficient time to qualify for a UPV.
As you are already considering marriage, this may well be your best option. Bear in mind that it's not permitted to switch from visitor to any other category of visa from within the UK.