Vitamin C: Helps to protect against future UVA and UVB sun damage by neutralizing free radicals. Helps to minimize the appearance of existing photo-damage. Helps to alleviate skin inflammation.
Vitamin E: Helps to neutralizes free radicals . Helps protect against UV damage and promotes healing. 
Ferulic acid: Found naturally in the seeds of some fruits, vegetables, nuts and grains, it offers anti-aging benefits by combating free radical damage.
Aqua / Water / Eau, Ethoxydiglycol, Ascorbic Acid, Glycerin, Propylene Glycol, Laureth-23, Phenoxyethanol, Tocopherol, Triethanolamine, Ferulic Acid, Panthenol, Sodium Hyaluronate

It can tingle for the first week or two, particularly on freshly cleansed skin. That usually settles as your skin adapts. If you have very reactive skin, rosacea, or a compromised barrier, start every other day and build up to daily. If C E Ferulic doesn't suit at all, Metacell Renewal B3 is a non-vitamin-C alternative, or C Tetra Advanced gives you a gentler form of vitamin C.

Yes, that's the L-ascorbic acid scent. It's distinctive and harmless. The smell becomes stronger as the formula oxidises with age, so if your bottle smells significantly stronger than when it was new, or has darkened to a deep orange-brown, it's time to replace it.

Yes. Use vitamin C in the morning and retinol at night, with no need to layer them in the same routine. If you're using SPF (which you should with vitamin C in your routine), it goes on top of the C E Ferulic in the morning.