I'm in CA. Make sure you understand the law before making offers. Note: I am not a lawyer and
this is not official legal advice, so you should always verify the below independently... .
Assets: Everything acquired during the marriage is split 50/50. You will have an uphill battle in court should you contest this. You are not obligated to give her anything acquired before and after. Of course you are welcome to do so.
Child support: You are only obligated to pay child support until each child reaches age 18, with extensions until the child finishes high school or special needs cases (e.g. learning disabilities, autism, down syndrome). Should you disagree on amounts, a court would more than likely enforce CA guideline support. You can calculate that number yourself at the
state guideline calculator website. The number obviously changes depending on % custody time and both of your incomes so if either of those changes, support should be recalculated. The state uses a "best interest of the child" standard and will almost always defer to this number should your wife contest any lower amount in the future. Be ready to offer this amount.
Spousal support: This number is negotiable. The guideline calculator above will also calculate a spousal support number, but in this case it's more of a guide. Most CA courts work to establish a spousal support plan that goes away after half the length of the marriage... .7.5 years in your case. However, due to the length of your marriage, your wife will always have the right to contest her current spousal support for the rest of her life or until she remarries, even if the support plan has phaseouts. She can legally waive this right, but expect to give her something in return (e.g. more assets, higher interim spousal support). Personally, I think this is a good buyout. Also note that while child support is not tax deductible for you, the spousal support is (and she pays taxes on the spousal support).
I suggest running some numbers at the above link so at least you have a starting point. Separate the child support from the spousal support since the child support number is practically a hard law in CA, plus you need to know both numbers for tax purposes anyway. Figure out a spousal support number you would be willing to pay and for how long (e.g. 80% of guideline for 7.5 years; 100% for 3 years, 50% for 2, then 25% for the the last 2.5; 100% for all 7.5 years with a waiver of future support).