No, you don't need to indicate future tense in casual conversation. Beginning Chinese learners get really tripped up on this. You actually sound more Chinese if you drop most attempts at putting tense or time in your sentences, and drop as many "me"s and "you's" as possible. ("I return house" 我回家了 sounds more native than "I'm going to go back to my house", which sounds super awkward. 我会回我的家了).

In fact, in conversation, you'll find that Chinese people may or may not indicate any tense at all. So, by western standards, this could mean "Dad bought you a lot of candy," (but this doesn't really make sense in context - he did buy the kid candy but that's not relevant just now), "Dad is buying you lots of candy." (but we know he's clearly not) or "Dad will buy you lots of candy" (which makes sense). 

Stuff like this is why texts like the Dao de Jing are essentially impossible to translate accurately - is the author telling a story about something that happened in the past? Giving a command about how to behave in the future? Through most of the philosophical books there's no tense, no structure, no nothing, just words, some of which have multiple meanings. So many of those translations are just educated stabs in the dark. I'm finding more and more that tense doesn't matter quite as much as we think it does. Our language is all wrapped up in knowing WHEN something happened. It's crucial, and alien to think otherwise. So the sooner you can set your brain to be a little more wishy-washy about exactly when something occurred, you'll find it easier to wrap your head around real Chinese. 

给你买 is also fine - it means the same thing as 买给你. Google this phrase in Chinese to see other examples of it being used.