Glad to know that you are interested in Enlight Cloud server 
Resources like RAM and CPU would auto-scale as per the load on the server and bandwidth will be used according to the traffic on the website. Web space is the only resource which can't auto-scale as its physically assigned to the VM. You have to manually increase/decrease it from your Enlight Control panel. There isn't any documentation of resource scalability because we can't provide the real time resource usage of a Live VM. We have a Billing predictor which has a option of "% Usage" where you can predict the actual % of resources which the VM will use.
You will be able to see the real time resource scalability of your VM from the Enlight control panel once you create a new VM. We have provided separate graphs for CPU, RAM, Bandwidth and Space usage in the Enlight Control panel which will help you to check the actual resources used by your VM.
You can set space and RAM according to your requirements. We will have to manually install Windows 2008 OS, Plesk, MailEnable, MySQL, SQL Server Express once you create a VM. There are no additional charges for installation. Only charges applicable would be the license cost.
As per our tests and research Enlight saves upto 60% of the monthly cost as its a pay per use server.
Charges of licensed applications are
Operating System
Windows 2008 Standard Edition (64 bit) :- £5/month
Windows 2008 Datacenter Edition (64 bit) :- £5/month
Control panel
Plesk 10 Domains - £3.00 GBP
Plesk 30 Domains - £5.00 GBP
Plesk 100 Domains - £10.00 GBP
Plesk Unlimited Domains - £15.00 GBP
cPanel/WHM - £5.00 GBP
Current offers on Enlight are
£5 off while signing up by using coupon code "Enlight"
£30 one time credit once your account becomes active
1 TB bandwidth free on each VM per month
Feel free to post if you have more queries related to Enlight.