Migrate Non-Profit Site to WordPress

I need our current website, www.naacaonline.org, moved in its entirety to a fresh WordPress installation. Every page, post, image, PDF, and piece of legacy content must come over so nothing is lost in the transition.

Core requirements
• A clean, responsive theme that reflects our small-nonprofit mission and keeps navigation simple for an older audience.
• Fully functional Event Calendar so we can publish hearings, trainings, and conference dates without touching code.
• A secure Members-Only area where logged-in users can read newsletters, view conference materials, and access internal documents.
• Straightforward workflow for staff to post annual-conference updates and quarterly newsletters.
• URL structure, basic on-page SEO, and any current redirects preserved to avoid breaking external links.

Deliverables
1. WordPress site running on our host, populated with all existing data.
2. Event Calendar and membership plugin configured and tested.
3. Step-by-step hand-off guide (screenshots or screencast) showing how we add events, restrict pages, and publish newsletters.
4. Two weeks of post-launch support for bug fixes or minor tweaks.

If you have recent experience migrating nonprofit or association sites and can recommend reliable plugins (e.g., The Events Calendar, MemberPress, or similar) let me know your approach and estimated timeline.