Backup, Backup, Backup no matter what you decide to do.
(a) will going back to yosmite also crash my laptop
without knowing why your Mac crashes, it is impossible to know if it will still crash with Yosemite.
You should really start a new 'Post' (see 'Post' button at the top of this page, and create a new post in the forum associated with the operating system you current have running). In your new post you should include the kernel panic reports (or at least a few of the most recent, to see if there is a trend, or if it is random)
1)
Kernel Panic reports: Finder -> Go -> Go to Folder -> /Library/Logs/DiagnosticReports
<http://support.apple.com/kb/ht2546>
<http://support.apple.com/en-us/HT200553>
The panic report should have "panic" in the file name.
2) also
Please post the EtreCheck output as a "Reply" to this thread
<https://discussions.apple.com/docs/DOC-6174> or <https://etrecheck.com>
Use the EtreCheck "Share" button to "Copy Report" (See the image below)
And then Paste in a "Reply" to this thread.
If, AND ONLY IF, you get the error:
"The message contains invalid characters"
then try posting to PasteBin.com, and give us a PasteBin URL link.
<http://pastebin.com/>
.
EtreCheck is a tool that helps Apple Support Community volunteers debug problems without any access to the troubled computers. Debugging problems can be a difficult task even when the machine is in front of you. Attempting it via a discussion forum is extremely difficult. EtreCheck is a great help that regards.
(b) what are the potential risks of going back to Yosmite
Apple is no longer providing security updates. Otherwise, if you are careful, then not too much
(c) do you have any other solutions for the above (1) and (2)
You should try an SMC reset and an NVRAM reset
<Reset the System Management Controller (SMC) on your Mac - Apple Support>
<How to reset NVRAM on your Mac - Apple Support>
Not sure if this will help, but it will not hurt either
Also seeing the EtreCheck output requested above would be useful.
Again, all of this should be in a new 'Post' in the forum associated with the operating system you are actually using at the moment.