How easy it will be for me to change the site colors and logo with my one once I install the site?

Using the special colors management page in the admin panel, you could easily change the site colors with different predefined ones or enter your own custom color code. You can also easily add your logo from the admin panel and change the colors on the site to match the main color of your logo. Or also if you prefer, we'll be happy to do that for you-you could just forward us your logo and we'll add it on the site (and resize it / crop it if necessary first) and adjust the colors to match it, as part of our free technical support.