Learn BS properly. Thanks me later.

Solve more 1600-1700s and spend hours on them. btw I'm ~1800 rated but I practice 2200-2400 and can sometimes solve them after lots of time, so 1600-1700 is reasonable

You can learn some basic algorithms, such as greed, binary search, binary answer, prefix sum, difference, dynamic programming and so on. In my opinion, usually the first three questions in the div2 competition almost do not use difficult algorithms. They are basically thinking questions. You can boldly make reasonable guesses and try to prove your answers. At the end of a competition, you can try to continue working on one or two problems that you did not work out in the competition. First of all, you can try to think for yourself. If you don't have any ideas within ten minutes, don't waste your time. Go to see the answers in time. Only through continuous accumulation can you improve. You can't only do what you can do in every competition. You should jump out of the comfort zone and challenge yourself to make progress.

first of all stop practicing problems which are rated below 1400. You have solved a hell lot of easy problems. set a rating range of 1400-1600 or 1500-1600 go to page 2 or 3 and just start solving each problem line by line. This worked for me.

Q3.Give me some source , where to do practice
I am using this site C2Ladder by codemastercpp and this site has a really good set of problems for each rating range. You should give it a try.

practice daily 2-3 question of avg 1200 for 10 days

1. Solve problems with a bit higher rating. If you encounter harder problem then think about it for some time, make sure you are learning from the problems.
2. You cannot solve any problem quickly. It's impossible. There are always problems which are easy for you and you are able to solve them immediately and problem which are hard for you and you need much time to solve them. Only way to solve problems quicker is to move up this boundary which separates easy problems from hard ones.
3. Codeforces is good place but you maybe want to try some other CP websites like AtCoder or CodeChef.

I think this repo will be helpful for you : Repo

You need to spend more time in coding. Problems over 1500-1700 level need to be solved and you need to have a good idea about the basics of graphs, trees, binary search and bits.... and "Stop Chatting with Girls”..because it wastes your important time ...I think the last one is the main obstacle on your way to becoming a specialist...

Just become an Expert and lose 100-200 rating