Trying to understand how the infantry anti-mech attacks rules work

[Banjulhu]

My group has recently taken up playing Battletech and have started to branch out from the basic rules to include things like tanks and infantry.

I've been looking into Elementals more because the 40k player in me appreciates power armoured zealots with jump packs and powerfists however the wording on how anti-mech attacks work, in particular the leg-attack has me a little stumped and my ability to find an answer on the internet is being stopped by what seems to be a never ending discussion over whether infantry is good enough or broken.

So leg-attacks state "Infantry units that begin a Weapon Attack Phase in the same hex and at the same elevation as the legs of an enemy ’Mech may choose to attack the ’Mech’s legs instead of making a standard weapon attack."

Does this mean that a unit of Elementals with their SRM-2s and lasers would have to give up both attacks in the Weapon Attack Phase if they share a hex with a mech to make a leg-attack or could they elect to not attack with one of their weapons to be able to make the leg-attack but still fire off the other weapon?

MOD Note:
Moved as this a how-to question not specific rules question.

[Lorcan Nagle]

You make weapon attacks, or a leg attack, or a swarm attack. With the leg attack you're basically fishing for crits.

[DevianID]

To the OP, yes you give up all shooting attacks to make a leg attack.

[MoneyLovinOgre4Hire]

A leg attack sacrifices damage in order to attempt to cripple the target's movement ability.

[Weirdo]

While it may be tempting to go for the higher raw damage of a weapon attack, leg attacks(especially against something big and slow) have the fun potential of setting up a vicious cycle, where the mech is slowed down and can't outrun the attacking troops, leaving it open to more attacks...and when it can no longer reliably stand, it becomes much more vulnerable to a swarm attack finishing it off.

[Charistoph]

It's even nastier if you're dealing with builds where they put Ammo in the Legs to keep it "safe".

So, Cripple with Leg Attacks.  Then when it falls, or is slowed down enough, Swarm to start stripping the Mech apart.

It gets more interesting if you're using the Enhanced Flamer rule from The Battlemech Manual, and the Flamers do both Damage AND Heat.