Latitude adapters

I have a Latitude D520 and recently bought a Latitude E6540. It will take me several months to fully configure the E6540 and in the meantime I want to be able to plug both laptops into the same power supplies so that I don't have to constantly unplug and plug in power adapters from their wall sockets. I have several places in the house where I have power adapters plugged in. I have three questions;

1)  The E6540 came with a 130W adapter but I have read in several forums that this is only required if using the docking station and that otherwise it will run happily on a 90W power supply without any performance hit. So I presume that my existing 90W power supply that I bought for use with the D520's docking station, can be used with the E6540, with no downside. Please could someone confirm whether I'm right about this?

2)   Can I safely use the 130W power supply that came with the E6540 with my D520? My understanding from other posts I have seen is that all Dell power supplies are modular and only output the current that the laptop they are attached to requires. So I presume that the 130W power supply will only output 65W when attached to the D520. But I thought I'd better double-check before trying it as I don't want to risk blowing up my D520!

3) I have read elsewhere that the E6540 can be used with a 65W power supply, although there is a significant performance hit if one does so. My E6540 has a 1TB SSD and no spinning disk, so I would have thought it would have a considerably lower power requirement than an E6540 that contained a spinning disk. Given that, would you expect my E6540 to be able to work more or less at full throttle with a 65W power supply or would there be a major performance hit despite the fact it doesn't contain a spinning disc?

Many thanks for any help you can give me.

Dave