Welcome to the site !!
You can get them anywhere , if you want OEM it is going to be Dealer or places like here that can get OEM parts , BUT , it is most likely going to take a while due to shipping delays , but any aftermarket grips will work as long as they are made for your bike , and should be readily available , so if you go online and search for "Grips for a 2013 Honda CRF110" you should be able to find plenty of them , then just choose the style and color you want , it should consist of the grip and another grip that is slightly larger to fit the throttle tube and some grip glue , or it will come complete with the throttle tube and the grip already glued one to it , and grip glue for the left side , or you can get bolt on grips (EMIG and/or ODI) , as they do not need glue and will simply slide on the left side and you tighten down a single Allen bolt and the grip is already on the throttle tube , and you choose the correct cam for your bike and you are done (these are what I use and will not go back to glue on grips) ..
As far as the oil goes , it could be a number of things , from the bike sitting , to oil rings , to valve guide seals ...you would need to test for compression and/or do a leak down test , to determine where the leak possibly is , if it is rings the air will blow into the crankcase (when on TDC) , if it is valve guide seals , it will be noticed into the head area where the cam is , or blowing out thru the carb , or out thru the exhaust ...
Hope that helped ....
