Working with SOAP API and Marketo Custom Object

Here are the requirements of my project:

Send personalized email to clients 30 days before the expiry dates of their product. 
Ex: Mr Client, Your Product A is expiring on August 21st. Please renew it now... 

Few constraint:
- A client can have multiple products (up to few hundreds)
- A client can have 10 product expiring the same day and ideally we should send only 1 email including the 10 product instead of 10 separate emails. 
- When a client buy a product, the information is currently stored in a in-house system. We would need to push this info to Marketo on a regular basis.
- I know, base on that Marketo Object Model article, that at the time of writing the article, it was not possible to: 

• view the data in records that exists in a Custom Objects belonging to a lead(s).
• directly use any data in records as the source for a dynamic value in a campaign, email, etc.

Is that still the true?


Here is how I'm thinking of doing this: 
1. Create a Marketo Custom Object to store the product information
2. Because I can't use the data of a Custom Object as a Token in a email, I was thinking of writing Javscript code to read the custom Object daily, copy the information (Product Name + Expiry Date) and paste it at the lead level in a custom field in order to use it as token in the emails. 
3. If that worked, I was thinking of having 1 custom fields to store all the product name expiryning the same day. That way I could list them all in the email. 

Now I have the following questions:
1. Am I crazy? Is that even doable?
2. Can I push on a daily basis Data from my in-house database to the Marketo Custom Object using the SOAP API? 
2. With the SOAP API, can I have access to the data stored in a Marketo Custom Field? 
3. Assuming I have acces to the data, with the SOAP API can I copy it into Lead Custom Fields? 
4. Any other idea to manage the issue of multiple product expirying the same day?

Thanks

Alex