I don't really understand the difference between Easy Money, Maximum Profit, Buy Bid & Sell Bid

After crafting an item in Guild Wars 2, you usually want to sell it for the best price and therefore will use the Trading Post and not sell it to a merchant.

When you open your trading post window, you can see the list of buying offers and the list of selling offers.
If you want to sell an item, you can choose to do so immediately by selling it to the highest buying offer available, or you can place a selling offer and wait for someone to buy it.
It is exactly the same process when buying an item. You can buy it immediately at the lowest selling offer available, or you can place a buying offer and wait for someone to sell it to you.

If the price of selling immediately (tax deduced) a crafted item is higher than the price of buying all of its components, then you are guaranteed to make profit. This is what the Easy Money does.

The other techniques are all using buy or sell offers, or both. With those, you would make more money but you would need to be more patient to buy the components/and or sell the crafted items.

To try to make the most gold with crafting, you obviously have to try to buy the components at the lowest possible price (placing buying orders) and sell the crafted item at the highest possible price (placing selling offers). To see those best opportunities, just have a look at the Maximum Profit page.

The 2 last techniques are a mix of offers and buying or selling directly.
If you want to buy directly the components, craft now, and sell later, you should go to Sell Bid
On the contrary, if you prefer to make an offer (that you can cancel at a later stage if you change your mind) to receive the components at the lowest possible price and craft them when you'll receive them, then you should open Buy Bid

Don't forget to click on the Plus to see more details.

When finding the best way to sell my component, how can I select which recipes to use?

To select or unselect the recipes you want to take into account for the computation of the best use for your components,
Select Recipes

How to know whether I am buying/selling directly or with an offer?

On the Easy Money, Maximum Profit, Buy Bid & Sell Bid pages, have a look at the very top of the page for details
Know if direct or offer for techniques
Here, I am using offer to sell, but buying the ingredients directly.

On the Recipe Details pages, you can directly switch the buying/selling mode by clicking on the "X"
Know if direct or offer for recipes
Here I am selling directly "Valkyrie Corrupted Scepter", buying directly "Shaman's Etched Scepter of Rage" and placing an offer to buy "Corrupted Lodestone"

On the Ingredients Details pages, you can directly switch the buying/selling mode by clicking on the Directly or Offer button.
Know if direct or offer for ingredients
Here I am buying ingredients directly, and selling the crafted item also directly.

Profit Displayed

The profit displayed in each pages includes the Trading Post Taxes.
If we are using a technique that includes offers (buying or selling), we always take the lowest existing selling offer, or the highest existing buying offer. When buying/selling in the game, we can of course adjust those amounts.

Technical Details

The website is using the Guild Wars 2 official API to update the price continuously. The price of each item is updated about every 2mn.

The benefit displayed is taking into account the Trading Post taxes.
If we are using one technique that includes offers, we are always taking the lowest selling offer available and the highest buying offer available. When buying or selling, you can of course adjust these prices.

Should I close my eyes and buy the components?

Of course not, you have first to check if you can craft this item (profession, level required and do I have or can I discover the recipe).
You also need to validate the price of the components and the crafted item, as the best opportunities never last long!
Also, if you are placing buying or selling offers, try to estimate if you have a chance to conclude a transaction.

Is this website Free?

Yes it is free, and it will always remain free.