The answer to your question is that there is no answer - there are just so many variables that it's really impossible to answer with anything quantitative.
The biggest variable is how much water is going down the drain. If you had a clog but very little water usage, it could be days before you saw anything on your basement floor. If you have a family of 8 taking showers every day it will show a lot quicker.
The smells start being noticable when sewage starts backing up on your floor, until then its unlikely you'd notice anything. Again, this can vary. If you are just putting fresh water down your drain, it might never smell. My neighbour didn't notice until they had several feet of water in their basement!
The rate of deteroiration will depend on age and condition of foundation beforehand, temperature, soil conditions, what the house was built on, quality of construction, thickness of foundation, etc.
As @DA01 says, the vast majority of basements with plumbing are arranged with septic/sewer lines that are lower than the basement floor.
To do otherwise requires pumping sewage, there is no other way. Excrement flows downhill. My first suggestion is DON'T! A sewage pump, like any other mechanical device, will fail eventually. If anyone misbehaves, it will fail sooner than might otherwise be expected, at least temporarily. Every time it fails, someone has to open the chamber it lives in up (smelly) and service it (yucky and smelly.) If that's not going to be you, you still get to smell it and you get to pay for it being yucky, smelly work.
If you choose to go there anyway, you can use normal plumbing fixtures and reduce the amount of yuck in the house somewhat by placing the sewage ejector pump in a copious (plan extra capacity for failures and power outages so things don't back up into the basement) basin exterior to the house with a manhole for access. You'll want an alarm system on this to notify you when there are problems with it. Using a rail & valve system that allows servicing the pump without having to enter the hole (pulling it up by an attached cable on a rail system that valves off the exit pipe when the pump is removed) will increase up-front cost but can lower service costs significantly.
My own septic system is religiously pump-free, at least in part because I have lived (in shared housing) where sewage was pumped uphill. Pump failures there have included a squirrel (or some sort of rodent carcass - presumably entering at the roof vent), non-flushable sanitary products that were flushed, bobby pins, pump wear from old age, every power outage. Additional failures have included failed check valves, non-functional float switches, and the pump becoming dislodged from its output connector.
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