Process for Indian man marrying Tajikistan woman in Bangalore

Dear All, Need your urgent advice/suggestion on how to proceed as I am totally new to the legal system and have no idea where to start & I'm panicking. In May 2016, I will be marrying a Tajikistan national in Bangalore, India (Legal marriage first then traditional one ). She will be coming to Bangalore, India from Tajikistan on tourist visa (6 months validity). I am an Indian basically from Bihar but living and working in Bangalore. We have known each other for over 5 years now and it will be time to settle with her in India for lifetime. We are both single and never married before. Below are few worries I have currently, if I missed anything please cover in answer if you can. It'd be a great deal for us both and very much appreciated. Q1. Where to begin, where to go, who to contact in Bangalore, what are the step by step processes to get legally married in India so she can be an India citizen and can work and live here in India permanently? Q2. What are the check-list of documents (Male & Female/both parties) required for entire process ? Q3. How much time & money ( Approx) would it cost to complete the entire process ? Q4. Do we have to register our marriage in her country as well or can she remain in India permanently and go visit her parents (Tajikistan) once in a while on tourist visa ? Q5. Can she keep her surname in marriage certificate or does she have to adopt my surname ? Q6. How easy or difficult is the entire process ? Any pros & Cons you can think of pls do mention. Q7. Is there any such thing as validity/expiry period for marriage certificate ? Q8. How can she later on bring her 5 yrs old sister from Tajikistan to stay & study here with us in India ? Please note I'm totally new to legal system and marriage both so would be great if you can explain the legal terminology & break it down for me to understand. Pls mention if anything that might come along down the road which I didn't ask here. Hoping to settle with the love of my life and share my success story soon. Thank you all in advance.