As mentioned above, a refractometer reading will need to be adjusted after fermentation has started. The reason is because the alcohol in the beer changes the reading. In your case, if you are getting an unadjusted reading of 1.036 after fermentation, then when you make the adjustment it looks like your beer finished out at about 1.015-1.016 which seems reasonable considering your mash temperature. If you would like to see a lower final gravity in your next batch, you could try mashing at 150F.
As far as yeast starters go, they serve several purposes with one of the primary purposes being to make sure that you are pitching enough yeast to do the job you are asking them to do. When you underpitch a beer, you will still get some yeast growth, however the chances of getting a stuck fermentation or having other fermentation problems go up. Since brewing is fairly labor intensive, you can look at the work of making a yeast starter as an insurance policy to make sure you are giving your beer the best chance at success.
One other consideration I didn't see mentioned is that your fermentation temperature of 70-75F seems to be on the high side for an IPA that would normally use Wyeast 1056 or another neutral strain. For that style of beer, I really try to keep the temp out of the 70s if at all possible - especially early on in fermentation.