Optimize & customize an existing Shopify Template to incorporate multiple products + bookings + postcode shipping. To be elegant solution

Using an existing Shopify template I wish to create a simple, elegant online store that has some advanced functionality. The store would need to handle Multiple Products with Multiple "add-ons" to these products. Additionally a "booking function" would be needed and "postcode" recognition for restricted shipping. I have already build a basic store through shopify and now wish to add the aforementioned functions. The order process would look like this: HOMEPAGE: - Slide Show: 3 pics (with ability to click through to cleanse options) ***new page*** - Choose a Cleanse Duration (1, 2, 4, 6 days): ***new page*** (if needed and is more elegant, open to suggestion) - Choose a Cleanse Type (Easy, Medium, Hard): Add Almond Milk (yes/no), Add Filitered Water (yes/no) - the cart will be update according to these having been added. - Choose a Cleanse commencement date: only specific days can be chosen and these days depend on the duration of the cleanse ordered (1 day: Sat, Mon, Wed... 2 day: Sat, Mon, Wed... 4 day: Sat & Mon... 6 Day: only Sat) - enter POSTCODE for Shipping Availability: We can only ship to City areas so this needs to be functional. - we will need specific instructions as to where to deliver to. - Order/Add to Cart *** check out & New page*** page Z: - Cart, only check out with paypal. ***New Page*** We also wish to have our "CONTACT US" page update to include a interactive email setting (email can be send to us straight from the site). It would include details: - Name, email, phone, comment I don't particularly mind if the shell of the above is created and then I can use my own creative discretion to make it look/feel/function how I want. The basic premise is to have the choice of products, add-on, postcode recognition and booking functionality set up to be as simple and elegant as possible to encourage sales. I would be looking to add and improve the site as we go and therefore would be seeking to develop a relationship with a developer and I know and trust. We also have a few other products that we wish to sell online and would seek to use the same developer if we are happy with them for these also. I hope to hear from you soon, Sam