which antennas for my Intel wireless card?

Hi,

unfortunately I'm sure about which antennas and cables to buy for my Intel AC 7260 card which has to fit into a fanless case.

This is the card: https://communities.intel.com/external-link.jspa?url=https%3A%2F%2Fwww.amazon.com%2FIntel-Wireless-AC-Network-Bluetooth-…

This kit to me looks all right:

Super Power Supply® 2 x 6dBi RP-SMA Dual Band 2.4GHz 5GHz + 2 x 8in / 20cm U.fl / IPEX Cable Antenna Mod Kit No Solderin…

Please do this kind of cables require soldering on the card or is it just a snap in installation?

Also, I some some antennas advertised for working on 2.4Ghz spectrum only and with a gain of 8dB (rather than 6). Are please all the same or should I be careful when choosing for them to be dual band and offering a certain dB value? I'm actually talking about this TP-Link antenna:

TP-Link TL-ANT2408CL Antenna Desktop Omnidirezionale, 2.4 Ghz, 8 dBi Indoor, Senza Cavo: Amazon.it: Informatica

Many thanks for help/support