Exclamation [Q] Lava 406q System Problems

Hi, Friends I am using LAVA iris 406q since 3months. And I am facing some Problems Please Help me to Solve it...

1) It Creates Automatically .thumbnails file and take Internal Storage's Memory until it gets full...

2) Big Problem is with RAM I am using smartphone with

4.Candy Crush,
5. Subway Surfers,
6. 3rd party music Player,
7. 360anti virus,
8. Clean masters,
9. Netqin Backup Syc
10. Live Train Enquiry,
11. ES File Explorer,
12. Google Maps,
13. Google Translate.
14. Video Converter,
15. MX Player,

Apps & My Daily Regular use with 1,2,3,4,5,6,7,8,15 number Apps. And after use I clean my Ram but don't know how it gets full and At Last Ram remains only 50,40,30 even 0 MB Ram. & I always have to Restart My smartphone Within 12-24hours But My Friends and Other People use their smartphone more time then Mine.

My Smartphone is not Rooted

Please Help me from This Problem.
Thanks & Regards