You'd have to be doing it a LOT to get their attention. It's against their TOS to write software to automate what you're talking about, but otherwise you should be okay.
If you whant to see how are your rankings verify with geoseo.com If you asck if SERPs are affected by you checking rankings that's a big NO
if checking our own ranking will effect our SERPs, who else on earth will put their site on google... or you want us to indexed our site and forget it? those thing will never happened. ^^
There's no wrong in checking your keywords in google. Checking your keywords won't hurt your rankings.
Google warns about this but I don't think it is a problem...they used to give out API keys which allowed a couple thousand requests per day...they stopped giving them out now
I think google warns about it because they don't want automated tools constantly checking keywords, but checking them often won't hurt your ranking at all.
Plus you don't want to click on your competitors much when you do check your position. Click through rates are a part of the algo.