Those plants are very small. I would give them alittle more time before flowering.
Not the same strain but close to each other as far as plant structure. Indica hybrids can vary widely but you can still run a couple different strains at a time successfully. You just need to research the growth patterns and find ones that will work together well. Look at grow diaries and journals of strains you want to run to get ideas of how they like to grow.
Yep, cloning is your best bet if your wanting to scrog or do see of green ect...
How do I clone them?
Use the search function, there are a ton of discussions here.
Honetly, the easiest way is cut a node off and throw it in a cup of water and than put it on a windowsill, it takes way longer but its the spend no money easy way. Change the water out every day or two.
You know you can edit your posts.