First, do read www.cregox.com/your-home
Don't give people logins like that. With squarespace, you can simply [invite them as contributors]( http://help.squarespace.com/guides/managing-contributor-permissions) but for analyzing your squarespace website all I should need is the URL. It's always open for visitors unless you've specifically disabled the pages.
Changing colors is usually a matter of a very simple Custom CSS. Even more often, it's much simpler than that - it's just changing the template style.
Having some kind of custom sidebar present in every page on a template that have none (do keep in mind a few squarespace templates have a sidebar feature) might become very complicated, as that will deal with responsive design. But I could do something nice there and if you need more later on we can discuss later development.
In any case, all your 3 items should cost me less than U$ 213 (unless I need much further research). And I would need a U$91 upfront payment along with admin access to the website. I can only promise delivery starting Tuesday 17th if you confirm both my requests 1 week before. I mean, if I get paid and access before next Wednesday for instance I will deliver it before Wednesday 18th.
The sooner you're okay to continue, the sooner I can start working on it. It will depend on my queue list of tasks.
If by any chance I do need a lot of further research, I'll let you know how much more it might cost (it will be U$21 per hour) and I can refund you 100% in case you don't want to continue. Although this is slightly unlikely.