Not specifying the salary of the employee in the contract

Q: I have a question for Mufti Saheb regarding a business contract for an employee. 

I am an optometrist and have my own optometry practice. It is the main source of my income to run my home. I am hiring another optometrist to run the business so that I can increase my studies. 

The going rate for an optometrist is around R25 000 a month in KZN. 

I have offered this person a salary of R15 000 with the incentive of earning 50% of the profits from the business every month. 

In the expenses of the business I have stipulated R25 000 as a salary for myself to run my expenses. I will still assist in the decision making and management of the practice. As the sole owner of the business. Is it permissible for me to take this R25 000 salary as part of the business expenses not to be included in the profit. 

The expenses are all shared with the optometrist I wish to hire so that there is full transparency.

Paying mahr in installments and wife claiming her mahr from husband's estate

Q: Is it allowed for the husband and wife to agree on terms/installments for the payment of mahr? Example: I'll pay you 1000 every month for 2 years. Is this OK or is it better to pay upfront one time even though it is less? 

If the husband dies, can the wife claim this remaining amount from the inheritance?

Keeping a wind chime in the garden

Q: I would like to know if it is permissible to keep a 'wind chime' in the garden? 

We moved into a house and there is a wind chime in the garden, and I am not sure if its something that we could keep, as it makes a noise when the wind picks up and the kids enjoy it, or should it be removed as the sound might be considered music?