Advice on Latitude E7470 with an i7 processor instead of i5

Hello,

I'm considering purchasing a Latitude E7470 ultrabook with

• an i7 processor (instead of the default i5 processor),
• 16 GB RAM (instead of the default 4GB) and
• 512 GB SSD (instead of the default 256 GB)

Now, I've overheard some laptop technicians informally say that the i7 processor produces way too much heat and also reduces battery life (or: the hours between 2 charge cycles). 

Could someone knowledgeable in the community confirm for me the following :

1. If the i7 processor (relative to the i5 processor) produces way too much heat, resulting in an overly hot keyboard most of the time, and/or in the CPU fan running most of the time, and/or making the laptop generally noisier to use?

2. If the i7 processor (relative to the i5 processor) significantly reduces battery life? For example, if some type of computing is resulting in 8 hours of battery life, how many hours per charge cycle could I expect from an i7 processor for the same computing?

3. Any general advice on whether to go or not go with i7?

Many thanks in advance.