Ask The Expert for Plumbing, Basement Waterproofing & Drain Cleaning Problems

We will be moving into a new home at the end of December. It is a new build, but we did not ask the builder to add abasement entrance. We want to know if it would be possible to finish the basement and turn into a rental property. How much would a separate entrance be to cut and install?
I just want to know why my basement room is leaking, above it is over unfinished concrete patio.
I had a sewer backup a couple of months ago due to City tree roots. The drain has since been cleared, but now I have a not-so-pleasant sewage smell coming from my sewer foundation drain in the basement. Do you have any idea what could be causing this smell. The drain is in the bathroom which is being used on a daily basis so I do not think it has anything to do with dry traps.
my house is 10 years old,I reacently noticed that my basment insolation is wet on the backyard side and detached side wall and some of the water is seaping in to concreate wall,but no water on the basment floor.pls suuggest what could create this leaking.
My downspout from the roof is backing up (bubbling back under heavy rain)? Does that fall under your expertise? What is your recommendation?
When it is wet like the weather we have been having lately, ground water is seeping form a drain in our cold cellar. I am not sure if it is related or not, but we are on a septic system. Please advise what is the most likely cause and solution to this water problem?
I have 2 water problems. Water is leaking into my basement from the foundation walls on both sides of my house. Also I have a poor water drainage problem in my backyard. Your assistance is appreciated.