Im looking for the best app to use to buy/sell on, is it as simple as transfering $ to an app (any advice on which one would be great - im in canada)
Binance and Coinbase are available for now. Look out for newly developed apps too but be careful about depositing there without knowing whom you are sending money to. Scams are common here and there is nobody to seek legal help from it you get scammed. However these two are trusted enough. Now it is not as easy as sending dollar to a digital payment method. I dont know how much you are aware of cryptocurrencies but you need to get yourself verified with a KYC/AML if you want full control over sending and withdrawing money to banks and so. Moreover you might face problems with banks if they are not compliant with crypto. So check with local residents of your country before signing up.
buying the type of coin i want to invest in then ideally selling when it gets to a level i am hoping it does?
That is a different topic altogether. Bitcoin and altcoin market are very unpredictable. You have learn how to read indicators and then its a roller coaster ride. Simple answer, read the charts, buy low, sell high, hold till you reach a target and dont panic because anxiety is what runs this market.
Im looking kfor access to the broadest range of coins, lower fees and high security if that helps any in recommendations?
All these are ideal conditions and there is no such app which is ideal. You have to try them out and see which one suits you along with what I wrote above.