There are several Indian-Chinese restaurants in Toronto, something that is rather difficult to find elsewhere it seems. Many of them are located in Scarborough, although you will also find a handful of them on the other end of town near the airport.
One of the longest-standing Indian-Chinese restaurants is Lin Garden in Scarborough, started by a Chinese couple from Calcutta. It's also one of the most revered places, although I haven't been there in a long time. You'll find good chili chicken, manchurian chicken, etc here.
Another place which you may never walk into solely based on the name, is a place called
Asian Wok'n'Roll in Mississauga near the airport. This is a place which I have visited in the recent past, and thoroughly enjoyed. We have tried many dishes, and are batting about 0.900 off this extensive menu. If you like your heat, you'll be happy (although I still always suggest requesting your heat). Oh, one thing to note -- this place is located in a little plaza, and there's an Indian-Chinese/hakka place right next door, which is not that great. I mention this because if you were facing both restaurants, one would likely choose the other one over Asian Wok'n'Roll, probably based on the name and the general vibe. Don't fall into this trap. And now that I think about it, a place across the street, China Garden, also gets some good praise for Indian-Chinese.
With regards to straight Indian, I'm actually at a loss, since when I'm home (west of Toronto) I'm usually eating South Asian food at home. The Devon equivalent in Toronto is Gerrard Street near the downtown area, but if you ask me, I think that area has declined greatly over the past several years. Nowadays, Mississauga is laden with Indian & Pakistani restaurants, several of which are apparently quite good. It's the "new Gerrard" if you ask me, which is nice since it means we don't have to head all the way into town. Brampton, also west of the city, is a highly-concentrated Indian community and is probably also well-populated with restaurants.
For chaat, one of my favourite places (which I haven't visited in a couple of years) is
Bombay Bhel. Their entrees are okay, but I wouldn't spend your appetite or dollars here for anything other than some chai and chaat. (I didn't realize they now have several locations, but that's what the website tells me)
One place I recently tried for breakfast was Tabaq, in Mississauga. It's located in a tiny, dumpy food court, that also houses South Indian, Korean, Pakistani, and Jamaican stalls. They have a great $2.99 breakfast of aloo, halwa, channa & poori. The aloo & halwa were pretty decent (although I was told they were sub-par that day, very likely due to them being completely overwhelmed, mostly by our party of 20

), but the channa were hands-down the best I've ever had. It's such a simple dish, and I never thought I'd encounter one that would make me re-evaluate my life like these ones did.
I'm not a big fan of Indian sweets and buffets in general, but I have to mention Brar Sweets & Restaurant for both their sweets and their buffet. Two (or three?) large cases of the most beautiful looking sweets, this place is the go-to place for sweets for many, many people. Their buffet, exclusively vegetarian, consists of impeccably clean and delicious daals, aloo ghobi, saag paneer, malai kofta, and about 10 other dishes. Rotis/naans hot off the press.
I'm sorry, but that's all I got on Indian off the top of my head. I'm afraid many of the other places I know are probably no longer.
Now I know you asked for Indian, but there is one Pakistani place close to my heart that I will mention. It's called Eastern Foods International, a tiny grocery store in Mississauga with a little counter in the back. They make some slammin' aloo parantha/keema paranthas, good rotis, and the best shammi kebabs I've had (outside my home

), as well as a very good biryani. A requisite stop everytime I'm home.
I would strongly recommend you head to the west side of town (Mississauga, Brampton) to find Indian and even the Indian-Chinese. This area is teeming with restaurants. You'll have a serious case of whiplash just driving around those nabes.
Have a great trip !
Lin Garden Restaurant
416-491-8484
1806 Pharmacy Avenue,
Scarborough, ON M1T 1H6
Asian Wok'n'Roll
905.671.8997
2919 Derry Rd E.
Mississauga, ON
5035 Hurontario St.
Mississauga, Ontario, L4Z 3X7
905.890.7955
Mon-Fri 12pm-3pm, 5pm-10pm
Sat, Sun 1pm-10pm
Tabaq
2580 Shepard Avenue
Mississauga, ON L5A 4K3
(905) 279-2345
Brar Sweets & Restaurant
755 Dundas St West
Mississauga, Ontario
Phone: 905-848-3933
Eastern Foods International
3071 Hurontario Street
Mississauga, ON L5A 2G9, Canada
(905) 276-1608