What exactly is covered with this Icelandic car rental? [closed]

We're going to have an one-week trip to Iceland in March. As we want to travel around the island, we decided to rent a small car. But I'm not sure if everything is covered by the offered insurance:

The car rental company (a broker for a local company) offers "Fully comprehensive insurance without excess" and "Theft protection without excess". You would have to pay a possible excess locally, but you can get a refund by the rental company at home. As an extra, you can book a "glass & tires" package.

Any insurance for sand & ash damages has to be bought locally with some excess - is this still refundable by the rental company? And is there any gravel protection package? Do we need that SCDW package anyways?

For clarity, here are the specific parts of the rental terms:

This partner offers you an insurance with reimbursement of the excess. In case of damage or theft of the vehicle, the deposit will be retained by the landlord as a deductible. After returning the car, send the invoice to our partners in due time and the amount will be refunded to you.

Additional insurances on site: If you are already insured by our partner Auto Europe with a' fully comprehensive insurance policy without excess', you do not need to take out any additional insurance locally.

The complete rental conditions for this offer:

Excess in case of damage: ISK 195,000.00, incl. VAT.

Super CDW: ISK 2,300.00, per day, incl. VAT, payable on site.

Reduces the collision deductible to ISK 25,000.00.

Sand and Ash Protection: Approximately ISK 1,900.00, per day, incl. VAT, payable on site. Excess applies of approximately ISK 195,000.00, incl. VAT.

CDW does not cover damages caused by sandstorms.

Excess in case of theft: Approx. ISK 195,000.00, incl. VAT.

PAI: Included in rates. Liability Insurance: Included in rates.

Fire Insurance: Included in all rates.

Auto Europe LLC has arranged your car rental booking with the car rental company listed on your voucher. Auto Europe LLC acts as an agency between you and the specified car rental company. For the purpose of car rental, Auto Europe LLC has accepted the payment of your reservation on behalf of the specified car rental company. This voucher is not a rental agreement and Auto Europe LLC itself is not a car rental company. At the time of renting, you enter into a rental agreement with the above-mentioned car rental company, which is subject to local legislation. Auto Europe LLC shall not be liable for any failure to comply with the above-mentioned car rental company's requirements or for any documents not available but necessary for rental. Additional fees can be charged by the car rental company on site, if this is the case. If the rental vehicle is picked up or returned outside of opening hours or additional services are requested on site, these fees are listed on your voucher in the rental terms and conditions of the car rental company in the local currency. The rental price is guaranteed in the above mentioned currency. All additional local charges not included in the rental price will be charged directly by the car rental company according to the local currency of the rental agreement/terms and conditions. As Auto Europe LLC acts as an intermediary, it is not possible to report VAT invoices. Auto Europe LLC, 39 Commercial Street, Portland, ME 04101 is a Limited Liability Company registered