Sheppard Ave. runs east/west across the top of the city, and will take about an hour to drive from one end to the other, in typical, daily traffic.
If you mean you will be working in the Sheppard/Yonge area, you're in luck. You don't even have to limit your search to that area, since the subway goes right to Yonge/Sheppard, and even the GO bus service runs to Finch, which is just 2 subway stops north of Sheppard (should you want to look north of the city: Thornhill, Markham, Richmond Hill, etc.). (A bit of trivia: Yonge Street is the longest street in the world, covering something like 1,500 miles, in total.)
The subway takes about 35 minutes between Sheppard & Union (downtown) stations, assuming everything is running smoothly. There is also the Sheppard line running east/west...although that's rather limited, given that it's such a new line. Look online for the Toronto Transit Commosion (TTC), for route information.
The average price of a 1 bedroom apartment in Toronto is about $1,200/month. It's possible to find them for less, but location and amenities will suffer, accordingly.
Residentially, the Yonge/Sheppard area is a mix of small, older homes which are slowly being replaced by monster homes (which take-up the whole lot), along with new condominium buildings going up everywhere there's space.
It's a bit of an older area of Toronto, and isn't really central to anything (banking, shopping, restaurants, etc.). There is a more affluent neighbourhood to the east, running along, and adjacent to, Bayview Avenue. One of the wealthiest areas of Toronto is off Bayview, south of Sheppard, closer to Lawrence Av.
That part of North York (one of the many boroughs of the Greater Toronto Area or GTA), the area along Yonge St., north of Sheppard, is primarily Asian and/or middle eastern. You will see many of the shop signs are in Korean or Arabic. (A bit of trivia: 52% of Torontonians were born outside Canada, and 47% consider themselves 'visible minorities'.)
South of Sheppard, along Yonge Street is...well...nothing. That is the main on and off ramp area for highway 401 (the main highway artery running across southern Ontario and, since it runs across the north of the city, is also one of the busiest "streets" in Toronto). (A bit of trivia: The 401 was once the widest highway in the world, with parts of it 20 lanes across - express and collector.) South on Yonge to York Mills, you come to one of Toronto's better restaurants (Auberge du Pommier), in where KPMG is located. ...About a 5 minute drive from Yonge/Sheppard.
Nearly all of Toronto is within a 15 minute walk of public transportation of some kind. Any residence located on a subway line is, naturally, going to be slightly more expensive than those on bus routes leading to subway stations, for obvious reasons. Parking and traffic is brutal in Toronto. When I lived in that part of town, on many occasions I'd spent nearly an hour in traffic, just getting a few blocks. During morning rush hour (which, in Toronto, is multiple hours), everyone is trying to go south, to downtown, along with traffic trying to get on and off the 401. That might be something to keep in mind, as well. Planning for "reverse rush hour" traffic will do you well.
No area of Toronto is unsafe, really. Notoriously, Jane & Finch has the highest crime rate, along with some unsavoury parts of downtown, and Scarborough (to the east of the city). But, still, despite being the 5th largest city in North America, the murder rate in Toronto is usually no more than about 1 per week, and nearly all of those are either domestic or drug/gang-related.
Over to the west, towards Bathurst, and south to Wilson, is a large Jewish community.
In all likelihood, you'll be looking at a condo. rental. Meaning, assuming you want something reasonably modern, you'll be renting a privately-owned condo. in a building where the apartments are privately-owned. There certainly are all kinds of rental opportunities in that part of town. Vacancy rates in Toronto tend to be pretty low, but you should be able to find something. In that part of Toronto you can find everything from shared or basement apartments, to rental townhouses, highrise and lowrise apartments, condo's, and homes. It mostly depends on what you want and how much money you have to spend. The average home price for that area will be about half a million, with smaller, older homes bringing down the average, and huge, monster homes raising the average. As I said, in many of the residential neighbourhoods in that area, you'll find tiny, older, matchbox homes next to giant monster homes, as the area slowly modernizes.
I hope that helps!