Windows 7 in hdd and Windows 10 in ssd-Dual boot

[Gyustarr]

Greetings.
I recently acquired a Windows 10 pro license and I wish to install in in an ssd. However in the same pc, I have pre-installed Windows 7 (oem) in hdd which I wish to keep for the foreseeable future . I have several questions about the procedure.
1) Will it affect my hdd in any way?
2)I'd like to have the choice to dual boot. Is there a feature that allows this in win10, or do I need some other software?
3)My pc is fairly old: It has legacy BIOS instead of UEFI. Will I run into any problems?
Thank you for your time.

 

[SkyNetRising]

I'd suggest installing windows 10 with only ssd present.
This way you'll be able to boot it even, if windows 7 hdd is later removed from system.

After you install windows 10 on SSD, connect back HDD and use bcdboot command to add boot entry of second OS to bootloader.

• bcdboot c:\windows /s H:

(C: - windows partition, H: - bootloader partition, Drive letters in recovery environment may be different)

Note. You have to use bcdboot from windows 7 recovery environment to to add boot entry for windows 7.
Same goes for windows 10 - You have to use bcdboot from windows 10 recovery environment to to add boot entry for windows 10. It will not work if you try to do it the other way.