How can I install Freya? Whether I need any unused partition to use it on Freya. or it will use the Windows 7 partitions.
Step 1: Getting Prepared:
Install windows first. (Since you already have Windows installed, that’s fine.)
Make Room for elementary :
Create a seperate partition for elementary. This will save you some time later.
Step 2: Install elementary:
Create a bootable usb.
After completely shutdown your system. Now connect your live usb, start your computer and change BIOS boot order. (Press Delete while booting, the key may be different for you)
Now select "Try elementary"
Now start installing elementary, Go through the installer until you reach an option that asks where (or how) you want to install the elementary. (This is the main step, be careful, simple mistake will wipe windows)
Case 1: If you have "Install elementary along side windows" option, then proceed with that option.
Case 2 : If you don't have the above option, select "something else" option.
See Install elementary OS in dual boot with 'something else' option
Will it slow down if I install both OS together ?
Probably not. It mainy depends on your RAM and your work. Create
Both should not Conflict with Partitions. In future I will any one OS. Can I do it without crash problems?
Create other partitions in ntfs format so that it can be recogniged by both elementary and freya. Also install elementary in extended partition.