I'm not a expert but as far I know if you apply for ROS before 90 days you're staying legally in Canada until get a answer.
If ROS is rejected you should leave Canada in a short period of time, but you won't be illegally as far you leave on time.
If finally you leave Canada while your PR in process you have to communicate to CIC immediately, providing your new address.
That van affects your PR application? It's depends of which stream you applied for but I don't think so, at least for CEC.
However can affects if you stay illegally here, but waiting for ROS, if applied on time, is safe.
My recommendation is be patience, wait for ROS answer, hope for the best and prepare for the worts: know how much time do you have to leave Canada if rejected, prepare to leave (if you expect to come back will be temporarily so you don't need to close bank accounts....)
In the meantime try to find any job with LMIA, it's not easy but is better try.