They have no bounty attached to them if that's what you're asking. If you're asking if they kill CS do you get the gold for it then the answer is yes.
Yeah the bounty.
May I ask what to build late game? I usually get boots + 3, HG and then Sheen.
Lich Bane and the Frozen Fist aren't really worth it, I wouldn't build a Sheen. Get your Sorc Boots and HG and then build according to who you are fighting. Are you against an AD? Build a Sunfire Cape, if not then build an Abyssal but you should end up with both.
Elise has a lot of build options, I'd recommend some of the following after you've finished your main four items:
Warmogs - Depending on the match up I'd consider building this quite early (but not before Sorc Boots or HG). Rylais - Has synergy with Liandry's and gives you a nice chunk of health. Zhonya's - It's active works well with her Spider E. Void Staff - She scales better with Mpen then with flat AP.
You should focus on building Mpen and Health with a bit of MR and Armour.