Hi there
With regard to hard points on wings, these are merely reinforced ribs that have been fitted with sockets or bolt holes to accomodate pylons and/or wiring to activate weapons or other stores.On some aircraft, the ribs are standard, unmodified ribs so as not to affect production.In some cases, the customer can modify those ribs as hardpoints later on.The carriage of external stores, apart from the obvious case of producing more drag, also increases the take-off roll, the landing roll, affects the climb rate, reduces the total load-carrying ability and affects the roll and pitch rate. Pylons can also differ, as some are "wet", ie, plumbed for fuel lines so as to be able to carry and jettison drop tanks or ferry tanks and some are dry, in that they can only carry dry stores such as bombs or gunpods.Some pylons are permanently attached to their parent aircraft as it's often too tedious and slow a job to casually change them.Some aircraft have the facility to blow off the pylons with an emergency squib if need be.
regards
GttC
