In regards to CBSA records, here's my opinion:
Since I first set foot in Canada I kept a calendar of dates that I went in and out of the country -- I frequently traveled to the US so I didn't want to risk getting my dates wrong. Despite of that, I ordered my CBSA records because I wanted to double check their info against mine -- it took less than 30 days and it was quite a simple form to fill up online, honestly I think it was worth it (in my case). If you are certain of your travel dates you probably don't need it unless you want to use their report instead of paying to get passport stamps translated (or at least I hear some people saying that the CBSA records are ok instead of translating stamps -- not sure about that since I think CIC always pulls CBSA records so why would they request stamps to be translated?).
Anyway, even with my own calendar kept along the years I found a few small differences which made it worth having the CBSA records (nothing that I think would make a big difference in my application, but still).
I requested records for the period starting 4 years from my application (before I was in Canada) and I can't see the harm in requesting records up to the date you requested them (the 4 year period preceding the application is what matters anyway, but it may "look good" to show that you maintained physical presence after your application).
Also keep in mind that in addition to entry records, CBSA has EXIT records starting from July 2013 which may also be helpful -- In my case I started making leisure "day trips" to the US right around July 2013 so now I have a comprehensive list of "day trips" I made (day trips don't have to be reported with the application but I will have to declare them if I get RQ, which is likely in my case because of all my travel).
