ILR Tier 1 Migrant - two questions

Hi there,
I am a Tier 1 migrant and have completed 5 years in that category. I am planning to apply for ILR in march along with two dependents - spouse and child. I have two questions and hoping somebody can help me out here.

1. Given the cost of each applicant, is it mandatory to apply for ILR of all the dependents with me? Can I apply now and dependents, let's say apply in 2017, all the while remaining as dependent on my current tier 1 visa which is valid till 2018? This is just so that I can offset the cost.

2. On this board - and anybody I spoke to - seems to have applied for ILR using PEO. Given that PEO is expensive, what's the issue with applying by post if your application is straightforward? Permanant job, not much out of UK, no criminal record and so on. Is it just the waiting times that people choose to use PEO.

Many thanks in advance
Sean

1. Yes, fine to apply separately. Note that fees go up in April.

2. You can apply by post or in person. It is your choice.

Additional 2 pence for point 2. Yes, it is the waiting times and not wanting to part with your passport for a period of 3 to 4 weeks would be the main reason I see people choose a PEO vs a Postal appointment. Another reason would be if there are complexities in the application then a PEO is seen as an opportunity to explain things to the CW.

I have had work colleagues do postal and receive their ILRs in 3 to 4 weeks time. So if you don't have travel plans and have a reasonably straightforward application, postal is the way to go.

Thanks CR001 and O_Relly.
O_Relly, it's reassuring to hear that people indeed get their ILR back in 3-4 weeks when applied by post, provided the application is straightforward. Postal is definitely the way forward for me.