3 Plugins for Magento 2.1

We have another website which we're putting together on Magento 2.1 at the moment, which actually sells tiles online. I need 3 plugins/extensions to do the following: 1. Calculate quantities for clients. We sell by the box, and our products are priced by the box. However, we need the client to see price per square metre. This is because each box doesn't necessarily hold 1sqm. When the client puts in the required area in sqm, the quantity box needs to populated by the number of boxes they need to cover this quantity. Each tile (product) is available in a number of options (customisable options). They are available in different sizes, colours, and finishes. Sometimes it may only be one custom (colour for example), sometimes it's a combination of these. We'll need to amend the attribute set so that we have an attribute called box area for example. This can contain the area in sqm inside the box. Unit price is the price per box. The exact thing I want can be found on this example: [login to view URL] The only difference I want is that the only price to be shown to the customer is the Sqm price, not the unit price. Also, their unit price is per piece, whereas mine will be by box. I also want the area calculator. And also of importance is the tick box which automatically increases the quantity by 10% (in area, then calculates boxes). 2. Request a sample. I need to be able to allow my clients to order a free sample, without creating any new products for this. Each sample order needs to be treated as any other order, so we can then chase who has ordered samples and so on. Samples. You'll also notice that there is a separate button to order a sample. If we can do this without adding samples to the product catalog that would be better. 3. Pay a deposit. We don't stock everything we sell. We have normal stock items, and special order items. If a product is a special order item, we need to allow the client to only pay 50% of the balance, with the remainder to be paid just before we deliver the goods. With the 50% invoice, I would prefer for accounting reasons that the invoice is raised for the total amount, and it automatically asks for only 50%, and then we have a way to send a link later to pay the remaining 50%. One of our competitor's website which runs on magento is http://firedearth.com. I'm not sure how many of these concepts they have on their website. There are a number of plugins available for older versions of magento, however, not for 2.1.1