Gel nails are made from products that are related to the acrylic family. They are typically a pre-mixed polymer and monomer gel that is first applied to the nails and then cured under ultra-violet lights.
Gel doesn't cure by exposing it to air. It uses the UV light emitted from the UV lamp to start the process of polymerization, and cure into the finished product.

First off know what you want and know what your paying for.  Many places can be misleading in prices and product and can be unsanitary to save a buck. Ask about the product, if its gel or acrylic, gel is usually more expensive then acrylic so if they tell you your getting gel and use powder in any step of the process and charge you for gel you are getting ripped off.  Make sure the technician changes the sanding bit on the drill in front of you and make sure they use a new file and give you your file when you leave. If you are a regular client, some salons might keep your file in a bag or an envelope with your name on it. Just make sure they don't reuse someone elses file on you!

Many discount salons will apply acrylic nails, then apply a thin layer of gel over the top and call them gel nails.
These are not gel nails, they are acrylic nails with a gel overlay. But you might get charged as if they were gel nails.
This is how you know if they are real gel nails…you must ask “Is there any powder involved in this process?." If they answer yes, then you know they are acrylic and not gel.
Most UV gel nails must be filed off unless they are a soak-off gel.

Shellac mani or pedi is a dry process that is usually done in 60 mins or less which includes filing of the nails, removal of the cuticles, then application of Luxio,Shellac,Gelish or any gel/polish in 3 phases under a UV light and finishing off with different oils and creams to moisturize the skin. This process ensures longer lasting of the product on.  You can request soaking of the hands or feet but this usually takes longer and will cost extra. 

Unless your allergic or have a bad reaction to a gel product (which is very rare) the answer is no. What wrecks your nails is if you don't take them off properly, like taking them off yourself or if the technician isn't trained properly and files your natural nail too much that it burns or causes pain. You should not experience pain when having your nails taken off or when you leave a salon, also your natural nail should look fine when you leave. Below is a picture of natural looking nails that just had gel removed, as you can see the nails look healthy.  If you experience otherwise like if your nails hurt or look unhealthy after removal, change salons or look for an experienced technician. Shellac, gel polish or soak-off gels should be soaked off with cotton and tin foil, do not let your fingers be soaked in a bowl of acetone. Regular Gel should be filed off carefully and the best way is to file as much as possible off without filing the natural nail bed and letting it fall off naturally so your nail isn't so weak underneath and grows out nicely.

This is method used to make feet appear beautiful, soft, smooth, shiny and well maintained with a gel overlay making the toe nails look fresh for a while.
A pedicure is a very good way to maintain the cleanliness of your feet. On a regular basis it helps prevent certain nail and skin diseases of the feet. It also removes the dead skin so that it may not become hard and rough.
The feet are properly moisturized and washed, using different kind of creams and lotions, to prevent the bottom of the feet from becoming dry and cracked.  This process can take up to 2 hours depending on what you get done.
Using Gel or colored gels on the toes can also cover damage nails by recreating the nail or covering up any blackness or imperfections on the nail.
Once the colored gel is applied which is like a polish it is cured and dried so no having to wait to put on your shoes and no need for flip flops, its great!

Gel Manicure is a cosmetic treatment for hands and nails that give a  natural, perfect and healthy look to nails.

Nowadays more concentration is given for proper removal of cuticles and applications of different oils and creams to balance the oils on base of nails.
Some people prefer gel on the natural nail after a manicure which can be french or colored gel, this gel is more like a nail polish that will cure under the UV light and you won't have to wait for it to dry. In most gel manicures a soak-off gel (no powder) is used.

Minx is a solid film with an adhesive back that is heat activated. Minx is made in California. Many celeberties have used Minx in their videos and to special events such as Beyonce, Rihanna, Lady Gaga, Mariah Carey, Pink etc. They are great for events.